Clinical analysis of prenatal stillbirth caused by umbilical cord torsion

Clinical analysis of prenatal stillbirth caused by umbilical cord torsion | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Clinical analysis of prenatal stillbirth caused by umbilical cord torsion Xizi Wu, Da Zhu, Xinwei Shi, Xiaoyan Xu, Guo Ai This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6985153/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Dec, 2025 Read the published version in BMC Pregnancy and Childbirth → Version 1 posted 17 You are reading this latest preprint version Abstract Objective This study aims to investigate the high-risk factors and ultrasonic examination of prenatal stillbirth caused by umbilical cord torsion (UCT). Method We retrospectively analyzed the electronic data of 424 pregnant women with UCT who delivered from January 2013 to February 2024 in Tongji Hospital, Tongji Medical College, University of Science and Technology. The subjects were divided into a stillbirth group (36 cases) and a live fetus group (388 cases) based on fetal conditions. In addition, demographic data, clinical manifestations, pregnancy complications and comorbidities, abnormalities of the fetus and its appendages, ultrasound diagnosis, as well as other data of the two groups were collected. The risk factors of stillbirth caused by UCT were analyzed through univariate and multivariate logistic regression analyses. Results Multiple Logistic regression analysis revealed that fetal growth restriction (FGR), history of decreased or vanished fetal movement, history of slow fetal heart rate, oligohydramnios, hydramnios, and umbilical cord root torsion at the umbilical chakra were independent risk factors for prenatal stillbirth caused by UCT (P 1). Based on ultrasonic examination, the missed diagnosis rate of UCT in the stillbirth group was 91.7%. Conclusion High-risk factors for prenatal stillbirth caused by UCT include FGR, a history of decreased or vanished fetal movement, a history of slow fetal heart rate, oligohydramnios, hydramnios, and umbilical cord root torsion at the umbilical wheel. Prenatal stillbirth is related to the position of the UCT rather than the number of weeks. Prenatal ultrasound detects UCT at a low rate. umbilical cord torsion prenatal stillbirth risk factors ultrasound Figures Figure 1 Figure 2 Background The umbilical cord is the only connection between the fetus and the mother, as well as the only avenue for the exchange of nutrients and substances between the two [ 1 ]. Intrauterine fetal death is an unpredictable complication in obstetrics, with an incidence of approximately 1.2% [ 2 ], with abnormal umbilical cord accounting for approximately 5% of stillbirth causes [ 3 ], which is usually acute and cannot be predicted or prevented [ 3 ]. Despite its low incidence i.e., approximately 2.1% − 10% [ 4 ], umbilical cord torsion (UCT) has a greater influence on perinatal infants and is difficult to diagnose before delivery. UCT is an uncommon obstetric complication and a rare cause of intrauterine fetal death [ 5 – 8 ]. Besides, it is an inevitable accidental event [ 8 ]. UCT is one of the unpredictable and difficult to prevent high-risk factors causing fetal death in utero. Detection of CT before birth can help minimize the perinatal mortality caused by UCT. At present, many studies on prenatal stillbirth caused by UCT have only focused on individual cases [ 3 , 6 ]. Nonetheless, this retrospective study with a large sample size on prenatal stillbirth caused by UCT aims to explore the high-risk factors of prenatal stillbirth caused by UCT and ultrasound examination. This work also seeks to search for the items requiring attention and effective preventive measures to reduce the incidence of prenatal stillbirth and prevent death. Methods Study design and population This was a retrospective cohort study designed to investigate the high-risk factors and ultrasonic examination of prenatal stillbirth caused by umbilical cord torsion (UCT). A total of 424 pregnant women with UCT who delivered in Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2013 to February 2024 were recruited as the study subjects. They were divided into a stillbirth group (n = 36) and a live fetus group (n = 388). Note that some patients might have experienced more than one pregnancy during the long-term study period. However, each pregnancy was regarded as a single sample regardless of the total number of females. The number of pregnancies, rather than the number of females, was included in the analysis as an independent variable. Inclusion criteria included Age ≥ 20 years; Gestational age greater than 20 weeks; Complete related information; Good language expression and communication skills. Exclusion criteria included Incomplete related information; Multifetal pregnancy, chromosome abnormalities, fetal malformations, induced labor due to social factors or other conditions, and stillbirth occurring during delivery; Patients with psychiatric diseases, cognitive disorders, or serious comorbidities; Ethics statement The study was reviewed and approved by the Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (TJ-IRB202403027). Written informed consent was not required for the study because of retrospective design and the use of fully anonymized data, all the information was obtained from the hospital’s electronic database. All procedures strictly adhered to the ethical principles of the Declaration of Helsinki. Data collection In our study, the data included maternal age, gravida, parity, IVF-ET, multipara ,maternal complications (GDM, HDP), gestational age at birth, fetal gender, fetal growth, umbilical artery blood flow, fetal movement, fetal heart rate, oligohydramnios, hydramnios, placenta velaria, battledore placenta, umbilical cord around the neck, excessively long cord, excessively short cord, single umbilical artery, thin umbilical cord, umbilical thrombosis, true umbilical cord knot, number of UCT coils, the position of UCT, fetal gender. Sonographic examinations Sonographic examinations were performed by physicians with a 5–9 MHz curved array volume transducer (GE Voluson S8, GE Voluson E8 and GE Voluson E10). The fetus and its appendages (umbilical cord, amniotic fluid, placenta) were examined by two-dimensional ultrasound (2DUS), three-dimensional ultrasound (3DUS) and power Doppler ultrasound. The specific steps for prenatal ultrasound examination are as follows: (1) Routine prenatal examination was performed to measure fetal size, check for fetal abnormalities, and record amniotic fluid. (2) The position where the umbilical cord was inserted into the placenta was identified, and an abnormal insertion was recorded. (3) Careful scanning was conducted along the umbilical cord to observe the umbilical cord entanglement, especially the entanglement of the umbilical cord root at the umbilical chakra. (4) The pitch values (along one side of the umbilical cord from the inner edge of the arterial or venous wall to the outer edge of the next coil) of three different umbilical cord segments were measured and recorded separately, and the average spiral length of the three segments was calculated. (5) The ratio of the systolic maximum blood flow velocity of the umbilical artery (S) to the end-diastolic blood flow velocity (D) was measured. Relevant definitions and diagnostic criteria Stillbirth is defined as the death of the fetus in utero after 20 weeks of gestation [ 9 ] and confirmed by the absence of fetal heartbeat through ultrasonography. Torsion of the umbilical cord was defined as ≥ 12 coils according to a Chinese perinatology study [ 10 ] and Strong's study [ 11 ], or prenatal umbilical coiling index (UCI) > 0.36[ 10 ]. The UCI was the ratio of the total number of coils on the umbilical cord to the length of the cord, as described by Strong et al [ 11 ]. The UCI was measured by ultrasound before delivery and calculated according to the method proposed by Sharma et al. We measured the distance between the coils, along one side of the umbilical cord from the inner edge of the arterial or venous wall to the outer edge of the next coil. The reciprocal of this distance in cm was the ultrasonological umbilical cord coiling index [ 10 ]. The final value was the average of the three different umbilical segments (one near the fetal insertion of the umbilical cord, one near the placental insertion, and one anywhere between the two) [ 10 ]. Confirmation Criteria: All cases for diagnosis were confirmed by direct visualization after delivery. Statistical analysis Data collection involved coding and entering participant information into IBM SPSS Statistics version 22.0. Statistical analyses were performed using both SPSS and GraphPad software. The measurement data of normal distribution were presented as mean ± standard deviation (M ± SD), and the T-test was used for comparison. The statistical data were expressed as numbers(%)and the Chi-square ( χ 2 ) test was used for comparison. Logistic regression analysis was used for multivariate analysis. P < 0.05 was considered statistically significant, and 95% confidence interval (CI) was calculated. Results The 36 women in the stillbirth group had an average age of 24–40 years, among which 31 (86.1%) were 24–34 years and 5 (13.9%) were ≥ 35 years. The Stillbirth group comprised 28 primiparas (77.8%) and 8 multiparas (22.2%). In the stillbirth group, there were 31 cases (86.1%) with regular birth examinations and 5 cases (13.9%) without regular birth examinations. The weeks of stillbirth ranged from 21 + 6 to 40 + 2 weeks, 7 cases (19.4%) from 21 + 6 to 27 + 6 weeks, 12 cases (33.3%) from 28 to 33 + 6 weeks, and 17 cases (47.2%) from 34 to 40 + 2 weeks. Compared with the live fetus group, the incidence of FGR, history of decreased or vanished fetal movement, history of slow fetal heart rate, oligohydramnios, hydramnios, excessively short cord, and umbilical cord root torsion at the umbilical chakra were significantly higher in the stillborn group (P < 0.05). There were no significant differences in the incidence of maternal factors, male fetus, history of absent or reversed end-diastolic umbilical artery blood flow, placental factors, umbilical cord around the neck, excessively long cord, single umbilical artery, thin umbilical cord, umbilical thrombosis, true umbilical cord knot, and UCT ≥ 30 coils between the two groups (P > 0.05) (Table 1 ). Table 1 Analysis of risk factors for prenatal stillbirth caused by UCT Characteristic The stillborn The live fetus t / X 2 P Group (n = 36) Group (n = 388) Maternal factor Advanced age 5 (13.9) 84 (21.6) 1.196 0.274 Age 30.17 ± 3.982 30.47 ± 4.561 0.438 0.664 Gravida 1.944 ± 1.194 2.034 ± 1.299 0.425 0.673 Parity 1.278 ± 0.513 1.356 ± 0.559 0.864 0.392 IVF-ET 1 (2.8) 39 (10.1) 2.040 0.153 Multipara 8 (22.2) 123 (31.7) 1.386 0.239 No regular birth check-up 5 (13.9) 32 (8.2) 1.316 0.251 GDM 5 (13.9) 81 (20.9) 0.995 0.319 HDP 4 (11.1) 46 (11.9) 0.018 0.895 Fetal factor Male fetus 17 (47.2) 190 (49.0) 3.691 0.055 FGR 15 (41.7) 66 (17.0) 12.96 < 0.001 History of absent or reversed end-diastolic umbilical artery blood flow 2 (5.6) 12 (3.1) 0.626 0.429 History of decreased or vanished fetal movement 22 (61.1) 30 (7.7) 87.24 < 0.001 History of slow fetal heart rate 4 (11.1) 7 (1.8) 11.29 < 0.001 Amniotic fluid factor Oligohydramnios 7 (19.4) 33 (8.5) 4.614 0.032 Hydramnios 12 (33.3) 29 (7.5) 25.22 < 0.001 Placental factor Placenta velaria 1 (2.8) 12 (3.1) 0.011 0.917 Battledore placenta 1 (2.8) 47 (12.1) 2.860 0.091 Umbilical cord factor Umbilical cord around the neck 7 (19.4) 95 (24.5) 0.458 0.499 Excessively long cord 1 (2.8) 18 (4.6) 0.267 0.606 Excessively short cord 2 (5.6) 2 (0.5) 8.955 0.003 Single umbilical artery 3 (8.3) 11 (2.8) 3.119 0.077 Thin umbilical cord 5 (13.9) 30 (7.7) 1.649 0.199 Umbilical thrombosis 1 (2.8) 8 (2.0) 0.081 0.776 True umbilical cord knot 1 (2.8) 12 (3.1) 0.011 0.917 UCT ≥ 30 coils 8 (22.2) 85 (21.9) 0.002 0.965 Umbilical cord root torsion at the umbilical chakra 11 (30.6) 7 (1.8) 66.99 < 0.001 IVF-ET, in vitro fertilization and embryo transfer; GDM, gestational diabetes mellitus; HDP, hypertensive disorders of pregnancy; FGR, fetal growth restriction; UCT, umbilical cord torsion. Multivariate Logistic regression revealed that FGR, history of decreased or vanished fetal movement, history of slow fetal heart rate, oligohydramnios, hydramnios, and umbilical cord root torsion at the umbilical chakra were independent risk factors for prenatal stillbirth caused by UCT (P 1) (Table 2 ). Table 2 Multivariate Logistic regression analysis of prenatal stillbirth with UCT Characteristic B SE Wald P OR 95% CI FGR 1.214 0.498 5.937 0.015 3.368 1.268–8.945 History of decreased or vanished fetal movement 2.874 0.499 33.149 < 0.001 17.712 6.658–47.119 History of slow fetal heart rate 1.736 0.825 4.427 0.035 5.673 1.126–28.582 Oligohydramnios 1.582 0.652 5.889 0.015 4.866 1.356–17.467 Hydramnios 1.881 0.578 10.589 0.001 6.559 2.113–20.362 Excessively short cord 0.235 1.849 0.016 0.899 1.264 0.034–47.392 Umbilical cord root torsion at the umbilical chakra 3.208 0.698 21.134 < 0.001 24.739 6.300-97.149 CI- 95% Confidence interval. The confirmed rate of prenatal ultrasound examination in the stillbirth group and the live fetus group was 8.3% and 9.8%, respectively, and the missed diagnosis rate was 91.7% and 90.2%, respectively (Table 3 ). Ultrasound diagnosed UCT (Fig. 1 a, 1 b, 1 c). Ultrasound missed umbilical cord torsion (Fig. 2 ). Table 3 Ultrasound examination of UCT Group Number of cases confirmed by ultrasound (n) Diagnosis rate % Missed diagnosis rate % The stillborn group (n = 36) 4 11.1 88.9 The live fetus group (n = 388) 35 9.0 91 Discussion The umbilical cord has one umbilical vein and two umbilical arteries. The umbilical artery is longer than the umbilical vein, whereas the umbilical vein is large and thin. The umbilical artery forms a physiological helix around the umbilical vein. Three blood vessels pass through the length of the umbilical cord in spiral or coiled fashions. The spiral fusion of these umbilical blood vessels is called spiral course [ 12 ]. The umbilical cord helix is one of the crucial characteristics of the umbilical cord [ 13 ], as it protects and supports the blood vessels of the umbilical cord. The causes of umbilical coil formation are unknown, and these hypotheses include: active or passive torsion of the embryo, movement and rotation of the fetus along the long axis of the umbilical cord, disproportionate growth of umbilical blood vessels, fetal hemodynamics, and arrangement of muscle fibers in the umbilical artery wall [ 14 , 15 ]. The physiological coil of the umbilical cord spans approximately 6–11 weeks with no adverse effects on the fetus. The UCT is formed if the umbilical cord coils for more than 11 weeks. The underlying mechanism of UCT remains unclear [ 8 ]. It may be associated with umbilical cord dysplasia, the sporadic thickness of Wharton’s jelly, and excessive fetal movements [ 16 ]. The umbilical cord is rich in Wharton’s jelly, which comprises a substantial amount of collagen and elastic fibers, which can protect and support blood vessels, and prevent the umbilical cord from being compressed, ensuring continuous blood flow [ 17 ]. The weakness is often distorted and narrowed in the absence of Watton's jelly locally [ 17 ]. UCT can cause twisting, narrowing, and occlusion of umbilical vessels, interruption of blood flow, and thrombosis [ 16 – 18 ]. It can also result in chronic hypoxia with severely reduced blood flow, oligohydramnios, and fetal growth retardation [ 3 ]. Complete blockade of the umbilical cord can also severely obstruct fetal-placental circulation with subsequent fetal death [ 2 , 5 , 8 , 18 ]. Herein, UCI was used to assess the extent of UCT. UCI can directly indicate the number of weeks of UCT and indirectly indicate the density of the umbilical cord helix. UCI was measured by ultrasound before delivery because postpartum UCI lacks the segment of the umbilical cord closest to the fetus, which tends to be more twisted than the part near the placental insertion [ 19 ]. In addition, antenatally the cord is more filled with blood, making the helix denser due to the intrinsic twist in the vessels [ 19 ]. After the umbilical cord is severed postpartum, the blood in the umbilical cord decreases, the umbilical cord contracts and the umbilical cord helix becomes less dense than before birth. Prenatal diagnosis of UC currently has shortcomings. The diagnosis is often confirmed after birth [ 18 ]. The main condition in the group of stillbirth caused by UCT was as follows: the rate of older pregnant women was lower than that of pregnant women of appropriate age, and the rate of multiparawas lower than that of primipara. Unscheduled birth check-ups wereless compared to regular birth check-ups; and even regular birth check-ups could not prevent stillbirth, accounting for86.1%. The rate of stillbirth at 34–40 + 2 weeks was the highest, reaching 47.2%. Pregnancy outcomes can be improved if such pregnant women can be timely admitted to a hospital and terminate their pregnancy. Research reports indicate that old age is associated with [ 10 , 20 ]. In the present study, the ratio of advanced age in the stillbirth group was lower than that in the live birth group; no significant correlation was noted between the two. Studies have reported a more relaxed abdominal wall of multipara and a wider uterine cavity, which is conducive to the free movement of the fetus and the formation of UCT [ 10 ]. The rate of multipara in the stillbirth group was lower than that in the live fetus group, and no significant correlation was noted between the two. Stillbirth can occur in pregnant women without regular birth check-ups. The rate of non-regular birth check-ups in the stillbirth group was higher than that in the live birth group; however, the two were not statistically significant. Regular prenatal check-ups cannot completely prevent the occurrence of stillbirth caused by UCT, and even stillbirth can occur within 3 days of prenatal examination, which is the current contradiction between doctors and patients. GDM is a key risk factor for UCT, which has a damaging effect on umbilical cord blood vessels and Wharton’s jelly [ 21 – 22 ]. The incidence of GDM in the stillbirth group was lower than that in the live birth group, and no significant correlation was noted between the two. No relevant studies have been found in previous literature, and the sample size needs to be expanded for further confirmation. A few studies argue that male fetuses are active and more prone to UCT. Here, the rate of male fetuses in the stillbirth group was lower than that in the live fetus group, and no statistical difference was observed between the two groups. Notably, FGR is one of the most prevalent complications in obstetrics and is often associated with premature birth and stillbirth. This causes reduced placental circulation, and the fetus is in a state of inadequate nutrient supply and poor metabolism, hence hindering fetal growth and development, causing FGR [ 10 ]. Fetuses with FGR have slower growth and development, reduced compensatory capacity, and are more likely to be stillborn after UCT. Decreased or vanished fetal movement, and slow fetal heart rate are early warning signs of intrauterine abnormalities, which may be caused by abnormal fetal blood supply. In this case, reduced fetal movement occurs even if the umbilical artery blood flow is not fully blocked [ 23 ]; the next step is interrupted blood flow, which results in stillbirth. Herein, the incidence of reduced or absent fetal movement was significantly higher in the stillbirth group (61.1%) than in the live birth group (7.7%). Fetal movement can predict fetal distress or near death earlier than fetal heart rate. Fetal movement can be reduced to disappear, which may last a few days to approximately one week; however, it may also quickly disappear. Nevertheless, the interval between the disappearance of fetal movement and that of the fetal heart can be up to 12–48 hours. The incidence of stillbirth reduces if the pregnancy is terminated when the fetal heart rate remains good. Therefore, when the fetal movement or the fetal heart rate is abnormal, the fetal situation should be first established, a timely ultrasound examination should be performed, and the umbilical cord should be carefully observed to improve the pregnancy outcome as far as possible. Amniotic fluid is an indispensable substance in the uterus that ensures normal fetal development. UCT obstructs umbilical blood flow and decreases the circulation of the placenta; the fetal blood circulation is redistributed to maintain blood supply to the brain and heart, whereas the renal blood flow and the fetal urine production to be reduced, causing oligohydramnios, which also weakens the buffering effect of amniotic fluid. The periuterine pressure directly acts on the fetal body when the uterine wall is close to the fetus and the uterus contracts, increasing the chance of umbilical cord compression, thereby influencing the fetal placental circulation, and further causing fetal distress or even death. In the case of hydramnios, the fetus has more room for movement and is more active, making it easier to UCT [ 16 ]. At the same time, UCT causes the umbilical cord to compress and narrow, thus obstructing the venous return, further causing increased leakage and hydramnios. Pilliod RA et al reported an increased incidence of stillbirth in pregnancies with hydramnios. Although the underlying cause is unknown, this will be the focus of future research [ 24 ]. Studies have shown that excessively long cord is associated with [ 10 ]. We found that the incidence of excessively long cords was lower in the stillbirth group than in the live fetus group; however, the two were not statistically significant. Univariate analysis revealed that the incidence of excessively short cording in the stillbirth group was higher than that in the live fetus group, whereas multivariate logistic regression showed no statistical difference. Further study should be conducted with larger sample sizes in the later stage. Studies have shown that a single umbilical artery is related to UCT [ 15 ]. The incidence of single umbilical artery was higher in the stillbirth group than in the live fetus group; however, there was no statistical significance between the two groups. It has been reported that when the umbilical cord is twisted ≥ 30 coils, the stillbirth rate is high. The rate of UCT ≥ 30 coils was higher in the stillbirth group than in the live fetus group; nonetheless, the two were not statistically significant. Torsion of the umbilical cord root at the umbilical chakra can result in cord root thinning and then cord-like necrosis, causing blood vessel occlusion or thrombosis, hence blocking the cord blood flow; the fetus eventually dies due to blood flow interruption. Other studies have revealed occurrences of intrauterine fetal death due to umbilical cord root torsion at the umbilical chakra [ 2 , 6 , 16 ]. Therefore, torsion location rather than the number of weeks is fundamental to the effect of UCT on the fetus. A careful examination of the umbilical cord in the umbilical chakra (where the umbilical cord enters the abdomen of the fetus) is necessary to prevent excessive twisting of the umbilical cord in such fetuses that could result in umbilical vessel blockage or even rupture. Besides, there is a need to identify the right time to terminate the pregnancy to prevent the risk of intrauterine fetal death [ 13 ]. Unfortunately, UCT is considered unpredictable and unpreventable. It is mechanical with no effective therapy. The pregnancy must be promptly terminated when its torsion endangers the fetus. The missed diagnosis rates of ultrasound examination in the stillbirth group and the live fetus group were 91.7% and 90.2%, respectively. Ultrasound examination is the first choice for prenatal detection of UCT; however, the rate of missed diagnosis remains high. The main reasons for missed diagnosis of UCT in ultrasonography include: (1) Prenatal ultrasonography hardly displays the whole and complete umbilical cord [ 16 ], particularly in the third trimester due to the large gestational age and fetal occlusion; (2)Influenced by amniotic fluid volume, fetal position, anterior wall placenta, and abdominal wall fat layer of pregnant women, part of the umbilical cord is difficult to display, especially the umbilical cord root at the umbilical chakra. (3) After intrauterine death, the blood in the umbilical cord stagnates, and ultrasound examination of umbilical blood flow has no blood flow signal, and the difficulty of ultrasound observation of UCT increases. Thus, there is a need to continuously improve the scanning skills during the actual examination, and perform multi-section and multi-angle scanning, especially the umbilical root at the umbilical chakra to improve the accuracy of ultrasonic diagnosis of UCT. Strengths and limitations This study is the first retrospective study with a large sample size to explore the high-risk factors of prenatal stillbirth caused by UCT and ultrasound examination. However, this study has some limitations as follows: (1) The stillbirth group (n = 36) is much smaller than the live fetus group (n = 388), which may affect the reliability of statistical comparisons, especially for rare outcomes. However, we included all positive cases during the study period without any loss in follow-up and exceeding the estimated sample size for sufficient representation. (2) Because of the retrospective nature, some interesting data might not be available or might be less reliable. (3) Although we excluded major confounding factors, such as medical conditions and multifetal pregnancies, other potential confounders; including socioeconomic background, cultural factors, and education, were not adjusted for in a multivariate analysis. Also, the effect of multiple pregnancies over time in the same women, which may influence the outcomes, was not considered for adjustment. (4) This is a single-center study involving cases from one hospital, the generalizability of our findings may be limited. But it could provide a foundation for future research. In the future, a multicenter, large-sample study should be conducted to validate our findings. Conclusion In conclusion, prenatal birth caused by UCT is highly unpredictable, unpreventable, and unavoidable. Ultrasound is the preferred method for umbilical cord examination, and it is difficult to precisely diagnose UCT before delivery. Ultrasound doctors should therefore focus on observing the degree of umbilical cord helix in pregnant women with the above high-risk factors, particularly the umbilical cord root at the umbilical chakra particularly to improve the diagnosis of UCT. However, prenatal ultrasound hardly indicates the severity of UCT; therefore, the monitoring of fetal movement is paramount. For pregnant women with UCT detected before birth, prenatal care should be strengthened. Pregnant women should be informed without alarm, of potential adverse consequences. Most fetal vascular lumens do not show significant narrowing, and hemodynamics do not see significant changes even if the umbilical cord is twisted. Most fetuses can be normally delivered, without significant severe neonatal complications. [ 15 , 25 ]. Nonetheless, such pregnant women need to be managed based on high-risk pregnancy. The fetal movement monitoring should also be strengthened to avoid missing the ideal time to see a doctor. Therefore, clinicians and sonographers should identify high-risk factors early, improve predictability and vigilance of UCT and its crises, and timely terminate pregnancy timely, to reduce the incidence of prenatal stillbirth. Abbreviations IVF-ET, in vitro fertilization and embryo transfer GDM, gestational diabetes mellitus HDP, hypertensive disorders of pregnancy FGR, fetal growth restriction UCT, umbilical cord torsion Declarations Acknowledgments The authors thank the Staff at the department of ultrasound, obstetrics, and pediatrics for their technical assistances and facility supports. Author contributions X.Z.W. contributed to conceptualization, proposal development, acquisition of data, data validation, data analysis，manuscript writing; D. Z. and X.W.S. contributed to acquisition of data, data validation，acquisition of images, final approval; X.Y.X. contributed to data analysis, formal analysis，manuscript revision, fund support，final approval; G.A. contributed to data analysis, formal analysis, manuscript revision, final approval; All authors have read and agreed to the published version of the manuscript. All authors have read and agreed to the published version of the manuscript. Funding The Key Research and Development Plan Projects in Hubei Province (2022BCA041). Data availability Data from this study are available from the corresponding author upon reasonable request. Ethics approval and consent to participate The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (Research ID:TJ-IRB202403027, Date of Approval 29 March 2024). Consent for publication Not applicable. Competing interests The authors declare no competing interests. Author details 1 Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan Hubei 430030, China. 2 Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan Hubei 430030, China. References Kalem MN, Kalem Z, Akgun N. Yuce E, Aktas H. 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Prenatal ultrasound findings regarding obstruction to blood flow and an umbilical artery varix caused by umbilical cord torsion. Eur J Obstet Gynecol Reprod Biol. 2022; 269:144-146. https://doi.org/10.1016/ j.ejogrb. 2021.12.014. Epub 2021 Dec 23. Bakotic BW, Boyd T, Poppiti R, Pflueger S. Recurrent umbilical cord torsion leading to fetal death in 3 subsequent pregnancies: a case report and review of the literature. Arch Pathol Lab Med. 2000;124 (9):1352-5. https://doi.org/10.5858/ 2000-124-1352-RUCTLT. Hashimoto S, Arakaki T, Takita H, Kaneko M, Matsuoka R, Sekizawa A. Prenatal diagnosis of the umbilical cord torsion at the placental cord insertion site: A case report and literature review. J Obstet Gynaecol Res. 2024;50 (9): 1728-1731. https://doi.org/10.1111/jog.16013. Epub 2024 Jul 2. Fleisch MC, Hoehn T. Intrauterine fetal death after multiple umbilical cord torsion-complication of a twin pregnancy following assisted reproduction. 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Analysis of factors associated with the umbilical cord pitch value by ultrasound measurement in late pregnancy. BMC Pregnancy Childbirth. 2023;23 (1):583. https://doi.org/10.1186/s12884-023-05894-x. Ma'ayeh M, McClennen E, Chamchad D, Geary M, Brest N, Gerson A. Hypercoiling of the umbilical cord in uncomplicated singleton pregnancies. J Perinat Med. 2018;46 (6):593-598. https://doi.org/10.1515/jpm-2017-0034. de Laat MW, Franx A, Bots ML, Visser GH, Nikkels PG. Umbilical coiling index in normal and complicated pregnancies. Obstet Gynecol. 2006;107 (5):1049-55. https://doi.org/10.1097/01.AOG.0000209197.84185.15. Tian CF, Kang MH, Wu W, Fu LJ. Relationship between pitch value or S/D ratio of torsion of cord and fetal outcome. Prenat Diagn. 2010;30(5): 454–458. https://doi.org/10.1002/pd.2499. Silver RM, Varner MW, Reddy U, et al. Work-up of stillbirth: a review of the evidence. Am J Obstet Gynecol. 2007;196 (5):433-44. https://doi.org/ 10.1016/j.ajog.2006.11.041. Machin GA, Ackerman J, Gilbert-Barness E. Abnormal umbilical cord coiling is associated with adverse perinatal outcomes. Pediatr Dev Pathol. 2000; (5): 462–471. https://doi.org/10.1007/s100240010103. de Laat MW, Franx A, van Alderen ED, et al. The umbilical coiling index, a review of the literature. J Matern Fetal Neonatal Med. 2005;17(2):93-100. https://doi.org/10.1080/14767050400028899. Ezimokhai M, Rizk DE, Thomas L. Maternal risk factors for abnormal vascular coiling of the umbilical cord. Am J Perinatol. 2000; 17 (8):441e5. https://doi.org/10.1055/s-2000-13452. Najafi L, Abedini A, Kadivar M, et al. Gestational diabetes mellitus: the correlation between umbilical coiling index, and intrapartum as well as neonatal outcomes. J Diabetes Metab Disord. 2019;18(1):51-57. https://doi.org/ 10.1007/s40200-019-00389-z.eCollection 2019 Jun. Ezimokhai M, Rizk DE, Thomas L. Thomas. Abnormal vascular coiling of the umbilical cord in gestational diabetes mellitus. Arch Physiol Biochem. 2001;109(3):209e14. https://doi.org/10.1076/apab.109.3.209.11593. Chen N, Qiu L, Luo H. A case report of umbilical cord torsion: Abnormal hemodynamics of the umbilical artery assessed by ultrasound. Eur J Obstet Gynecol Reprod Biol. 2023;285 214-216. https://doi.org/ 10.1016/ j.ejogrb. 2023.04. 015. Epub 2023 Apr 19. Pilliod RA, Page JM, Burwick RM, Kaimal AJ, Cheng YW, Caughey AB. Caughey. The risk of fetal death in nonanomalous pregnancies affected by polyhydramnios. Am J Obstet Gynecol. 2015;213 (3): 410.e1-6. https://doi.org/ 10.1016 /j.ajog.2015.05.022. Epub 2015 May 14. Predanic M, Perni SC, Chervenak FA. Antenatal umbilical coiling index and Doppler flow characteristics. Ultrasound Obstet Gynecol. 2006;28 (5): 699–703. https://doi.org/10.1002/uog.2745. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6985153","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":486487984,"identity":"2f51fd8b-2fbb-4063-b504-4c8d271475ea","order_by":0,"name":"Xizi Wu","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Xizi","middleName":"","lastName":"Wu","suffix":""},{"id":486487985,"identity":"a240ca17-b0ec-4bfb-b894-30f1cddff23c","order_by":1,"name":"Da Zhu","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Da","middleName":"","lastName":"Zhu","suffix":""},{"id":486487986,"identity":"b8ae225e-fc48-412d-926f-bf8eb7f36ba6","order_by":2,"name":"Xinwei Shi","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Xinwei","middleName":"","lastName":"Shi","suffix":""},{"id":486487987,"identity":"3c1ce681-5ab6-4efe-a4b4-26cc7a9c7fae","order_by":3,"name":"Xiaoyan Xu","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Xiaoyan","middleName":"","lastName":"Xu","suffix":""},{"id":486487988,"identity":"0b58d63e-caad-4d6b-9d39-2251b2940772","order_by":4,"name":"Guo Ai","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuklEQVRIiWNgGAWjYDACZjDJJgdlEK0lgc2YBC1gkMCQ2EC0Yv529msSH3/wpc9v5z34gaHGJpqgFonDPGWSMxLYcjcc5kuWYDiWlkvYusM8adI8IC3MPAYSjA2HCWuRh2pJl2/mMf5BlBaDw+zHQFoSgNaZEWeL4WEeZssZaWyGG4BaLBKI8Yvc+eMPb3ywOSYv33/G+MaHGhsivM/AYwAkjkHYCYSVgwD7AyBRQ5zaUTAKRsEoGJkAAK76Nsk9no60AAAAAElFTkSuQmCC","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Guo","middleName":"","lastName":"Ai","suffix":""}],"badges":[],"createdAt":"2025-06-26 15:53:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6985153/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6985153/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12884-025-08524-w","type":"published","date":"2025-12-10T15:57:16+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":87269822,"identity":"1a826e36-3952-49c7-8bc3-1cb5eeae53c8","added_by":"auto","created_at":"2025-07-22 08:17:05","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":886152,"visible":true,"origin":"","legend":"\u003cp\u003eLive fetus with UCT at 37\u003csup\u003e+6\u003c/sup\u003e weeks. UCT images by two-dimensional ultrasound(a) and color Doppler ultrasound diagnosis(b), postnatal stereogram of UCT(c).\u003c/p\u003e","description":"","filename":"fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6985153/v1/e2285107996fa77525598b39.jpg"},{"id":87269830,"identity":"6123c2f4-5f4a-4ebe-8935-fbaa1db06e07","added_by":"auto","created_at":"2025-07-22 08:17:05","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":5218517,"visible":true,"origin":"","legend":"\u003cp\u003eStillbirth caused by UCT at 27+4 weeks. Postnatal stereogram of UCT, including umbilical root torsion at the umbilical chakra.\u003c/p\u003e","description":"","filename":"fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6985153/v1/5ec2bf92142b3c5a8c9657ee.jpg"},{"id":98243502,"identity":"5c3c118b-5dcb-491b-a006-3193e3c74736","added_by":"auto","created_at":"2025-12-15 16:07:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6885480,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6985153/v1/49b09921-a421-4073-aa81-146251027076.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Clinical analysis of prenatal stillbirth caused by umbilical cord torsion","fulltext":[{"header":"Background","content":"\u003cp\u003eThe umbilical cord is the only connection between the fetus and the mother, as well as the only avenue for the exchange of nutrients and substances between the two [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Intrauterine fetal death is an unpredictable complication in obstetrics, with an incidence of approximately 1.2% [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], with abnormal umbilical cord accounting for approximately 5% of stillbirth causes [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], which is usually acute and cannot be predicted or prevented [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Despite its low incidence i.e., approximately 2.1% \u0026minus;\u0026thinsp;10% [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], umbilical cord torsion (UCT) has a greater influence on perinatal infants and is difficult to diagnose before delivery. UCT is an uncommon obstetric complication and a rare cause of intrauterine fetal death [\u003cspan additionalcitationids=\"CR6 CR7\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Besides, it is an inevitable accidental event [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. UCT is one of the unpredictable and difficult to prevent high-risk factors causing fetal death in utero. Detection of CT before birth can help minimize the perinatal mortality caused by UCT. At present, many studies on prenatal stillbirth caused by UCT have only focused on individual cases [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eNonetheless, this retrospective study with a large sample size on prenatal stillbirth caused by UCT aims to explore the high-risk factors of prenatal stillbirth caused by UCT and ultrasound examination. This work also seeks to search for the items requiring attention and effective preventive measures to reduce the incidence of prenatal stillbirth and prevent death.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy design and population\u003c/h2\u003e\u003cp\u003eThis was a retrospective cohort study designed to investigate the high-risk factors and ultrasonic examination of prenatal stillbirth caused by umbilical cord torsion (UCT). A total of 424 pregnant women with UCT who delivered in Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2013 to February 2024 were recruited as the study subjects. They were divided into a stillbirth group (n\u0026thinsp;=\u0026thinsp;36) and a live fetus group (n\u0026thinsp;=\u0026thinsp;388).\u003c/p\u003e\u003cp\u003eNote that some patients might have experienced more than one pregnancy during the long-term study period. However, each pregnancy was regarded as a single sample regardless of the total number of females. The number of pregnancies, rather than the number of females, was included in the analysis as an independent variable.\u003c/p\u003e\u003cp\u003e\u003cb\u003eInclusion criteria included\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eAge\u0026thinsp;\u0026ge;\u0026thinsp;20 years;\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eGestational age greater than 20 weeks;\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eComplete related information;\u003c/p\u003e\u003c/li\u003e\u003cli\u003eGood language expression and communication skills.\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003cp\u003e\u003cb\u003eExclusion criteria included\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eIncomplete related information;\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eMultifetal pregnancy, chromosome abnormalities, fetal malformations, induced labor due to social factors or other conditions, and stillbirth occurring during delivery;\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003ePatients with psychiatric diseases, cognitive disorders, or serious comorbidities;\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eEthics statement\u003c/h3\u003e\n\u003cp\u003e The study was reviewed and approved by the Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (TJ-IRB202403027). Written informed consent was not required for the study because of retrospective design and the use of fully anonymized data, all the information was obtained from the hospital\u0026rsquo;s electronic database. All procedures strictly adhered to the ethical principles of the Declaration of Helsinki.\u003c/p\u003e\n\u003ch3\u003eData collection\u003c/h3\u003e\n\u003cp\u003eIn our study, the data included maternal age, gravida, parity, IVF-ET, multipara ,maternal complications (GDM, HDP), gestational age at birth, fetal gender, fetal growth, umbilical artery blood flow, fetal movement, fetal heart rate, oligohydramnios, hydramnios, placenta velaria, battledore placenta, umbilical cord around the neck, excessively long cord, excessively short cord, single umbilical artery, thin umbilical cord, umbilical thrombosis, true umbilical cord knot, number of UCT coils, the position of UCT, fetal gender.\u003c/p\u003e\n\u003ch3\u003eSonographic examinations\u003c/h3\u003e\n\u003cp\u003eSonographic examinations were performed by physicians with a 5\u0026ndash;9 MHz curved array volume transducer (GE Voluson S8, GE Voluson E8 and GE Voluson E10). The fetus and its appendages (umbilical cord, amniotic fluid, placenta) were examined by two-dimensional ultrasound (2DUS), three-dimensional ultrasound (3DUS) and power Doppler ultrasound. The specific steps for prenatal ultrasound examination are as follows: (1) Routine prenatal examination was performed to measure fetal size, check for fetal abnormalities, and record amniotic fluid. (2) The position where the umbilical cord was inserted into the placenta was identified, and an abnormal insertion was recorded. (3) Careful scanning was conducted along the umbilical cord to observe the umbilical cord entanglement, especially the entanglement of the umbilical cord root at the umbilical chakra. (4) The pitch values (along one side of the umbilical cord from the inner edge of the arterial or venous wall to the outer edge of the next coil) of three different umbilical cord segments were measured and recorded separately, and the average spiral length of the three segments was calculated. (5) The ratio of the systolic maximum blood flow velocity of the umbilical artery (S) to the end-diastolic blood flow velocity (D) was measured.\u003c/p\u003e\n\u003ch3\u003eRelevant definitions and diagnostic criteria\u003c/h3\u003e\n\u003cp\u003eStillbirth is defined as the death of the fetus in utero after 20 weeks of gestation [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] and confirmed by the absence of fetal heartbeat through ultrasonography. Torsion of the umbilical cord was defined as \u0026ge;\u0026thinsp;12 coils according to a Chinese perinatology study [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and Strong's study [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], or prenatal umbilical coiling index (UCI)\u0026thinsp;\u0026gt;\u0026thinsp;0.36[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The UCI was the ratio of the total number of coils on the umbilical cord to the length of the cord, as described by Strong et al [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The UCI was measured by ultrasound before delivery and calculated according to the method proposed by Sharma et al. We measured the distance between the coils, along one side of the umbilical cord from the inner edge of the arterial or venous wall to the outer edge of the next coil. The reciprocal of this distance in cm was the ultrasonological umbilical cord coiling index [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The final value was the average of the three different umbilical segments (one near the fetal insertion of the umbilical cord, one near the placental insertion, and one anywhere between the two) [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Confirmation Criteria: All cases for diagnosis were confirmed by direct visualization after delivery.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003e Data collection involved coding and entering participant information into IBM SPSS Statistics version 22.0. Statistical analyses were performed using both SPSS and GraphPad software. The measurement data of normal distribution were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (M\u0026thinsp;\u0026plusmn;\u0026thinsp;SD), and the T-test was used for comparison. The statistical data were expressed as numbers(%)and the Chi-square (\u003cem\u003eχ\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e) test was used for comparison. Logistic regression analysis was used for multivariate analysis. \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant, and 95% confidence interval (CI) was calculated.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe 36 women in the stillbirth group had an average age of 24\u0026ndash;40 years, among which 31 (86.1%) were 24\u0026ndash;34 years and 5 (13.9%) were \u0026ge;\u0026thinsp;35 years. The Stillbirth group comprised 28 primiparas (77.8%) and 8 multiparas (22.2%). In the stillbirth group, there were 31 cases (86.1%) with regular birth examinations and 5 cases (13.9%) without regular birth examinations. The weeks of stillbirth ranged from 21\u003csup\u003e+\u0026thinsp;6\u003c/sup\u003e to 40\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e weeks, 7 cases (19.4%) from 21\u003csup\u003e+\u0026thinsp;6\u003c/sup\u003e to 27\u003csup\u003e+\u0026thinsp;6\u003c/sup\u003e weeks, 12 cases (33.3%) from 28 to 33\u003csup\u003e+\u0026thinsp;6\u003c/sup\u003e weeks, and 17 cases (47.2%) from 34 to 40\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e weeks.\u003c/p\u003e\u003cp\u003eCompared with the live fetus group, the incidence of FGR, history of decreased or vanished fetal movement, history of slow fetal heart rate, oligohydramnios, hydramnios, excessively short cord, and umbilical cord root torsion at the umbilical chakra were significantly higher in the stillborn group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). There were no significant differences in the incidence of maternal factors, male fetus, history of absent or reversed end-diastolic umbilical artery blood flow, placental factors, umbilical cord around the neck, excessively long cord, single umbilical artery, thin umbilical cord, umbilical thrombosis, true umbilical cord knot, and UCT\u0026thinsp;\u0026ge;\u0026thinsp;30 coils between the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAnalysis of risk factors for prenatal stillbirth caused by UCT\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eCharacteristic\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe stillborn\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe live fetus\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e/\u003cem\u003eX\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGroup\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;36)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGroup\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;388)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaternal factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAdvanced age\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e5 (13.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e84 (21.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.196\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.274\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e30.17\u0026thinsp;\u0026plusmn;\u0026thinsp;3.982\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e30.47\u0026thinsp;\u0026plusmn;\u0026thinsp;4.561\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.438\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.664\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGravida\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.944\u0026thinsp;\u0026plusmn;\u0026thinsp;1.194\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2.034\u0026thinsp;\u0026plusmn;\u0026thinsp;1.299\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.425\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.673\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.278\u0026thinsp;\u0026plusmn;\u0026thinsp;0.513\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.356\u0026thinsp;\u0026plusmn;\u0026thinsp;0.559\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.864\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.392\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIVF-ET\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1 (2.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e39 (10.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.040\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.153\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMultipara\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e8 (22.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e123 (31.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.386\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.239\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNo regular birth check-up\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e5 (13.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e32 (8.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.316\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.251\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGDM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e5 (13.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e81 (20.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.995\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.319\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHDP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4 (11.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e46 (11.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.895\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFetal factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale fetus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e17 (47.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e190 (49.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.691\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.055\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFGR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15 (41.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e66 (17.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e12.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistory of absent or reversed end-diastolic umbilical artery blood flow\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2 (5.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e12 (3.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.626\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.429\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistory of decreased or vanished fetal movement\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e22 (61.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e30 (7.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e87.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistory of slow fetal heart rate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4 (11.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e7 (1.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e11.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAmniotic fluid factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOligohydramnios\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e7 (19.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e33 (8.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4.614\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.032\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHydramnios\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e12 (33.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e29 (7.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e25.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlacental factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlacenta velaria\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1 (2.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e12 (3.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.011\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.917\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBattledore placenta\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1 (2.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e47 (12.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.860\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.091\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUmbilical cord factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUmbilical cord around the neck\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e7 (19.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e95 (24.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.458\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.499\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExcessively long cord\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1 (2.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e18 (4.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.267\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.606\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExcessively short cord\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2 (5.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2 (0.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e8.955\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.003\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSingle umbilical artery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3 (8.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e11 (2.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.119\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.077\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThin umbilical cord\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e5 (13.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e30 (7.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.649\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.199\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUmbilical thrombosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1 (2.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e8 (2.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.081\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.776\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTrue umbilical cord knot\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1 (2.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e12 (3.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.011\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.917\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUCT\u0026thinsp;\u0026ge;\u0026thinsp;30 coils\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e8 (22.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e85 (21.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.002\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.965\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUmbilical cord root torsion at the umbilical chakra\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e11 (30.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e7 (1.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e66.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eIVF-ET, in vitro fertilization and embryo transfer; GDM, gestational diabetes mellitus; HDP, hypertensive disorders of pregnancy; FGR, fetal growth restriction; UCT, umbilical cord torsion.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eMultivariate Logistic regression revealed that FGR, history of decreased or vanished fetal movement, history of slow fetal heart rate, oligohydramnios, hydramnios, and umbilical cord root torsion at the umbilical chakra were independent risk factors for prenatal stillbirth caused by UCT (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, OR\u0026thinsp;\u0026gt;\u0026thinsp;1) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMultivariate Logistic regression analysis of prenatal stillbirth with UCT\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCharacteristic\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eB\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eSE\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003eWald\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003eOR\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e95% \u003cem\u003eCI\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFGR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.214\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.498\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e5.937\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.015\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e3.368\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.268\u0026ndash;8.945\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistory of decreased or vanished fetal movement\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.874\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.499\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e33.149\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e17.712\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e6.658\u0026ndash;47.119\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistory of slow fetal heart rate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.736\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.825\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4.427\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.035\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e5.673\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.126\u0026ndash;28.582\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOligohydramnios\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.582\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.652\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e5.889\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.015\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e4.866\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.356\u0026ndash;17.467\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHydramnios\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.881\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.578\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e10.589\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e6.559\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.113\u0026ndash;20.362\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExcessively short cord\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.235\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.849\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.016\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.899\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.264\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.034\u0026ndash;47.392\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUmbilical cord root torsion at the umbilical chakra\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3.208\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.698\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e21.134\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e24.739\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e6.300-97.149\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003eCI- 95% Confidence interval.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe confirmed rate of prenatal ultrasound examination in the stillbirth group and the live fetus group was 8.3% and 9.8%, respectively, and the missed diagnosis rate was 91.7% and 90.2%, respectively (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Ultrasound diagnosed UCT (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea,\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb,\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). Ultrasound missed umbilical cord torsion (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eUltrasound examination of UCT\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroup\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNumber of cases confirmed by ultrasound (n)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDiagnosis rate %\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMissed diagnosis rate %\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThe stillborn group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;36)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e11.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e88.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThe live fetus group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;388)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e9.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e91\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe umbilical cord has one umbilical vein and two umbilical arteries. The umbilical artery is longer than the umbilical vein, whereas the umbilical vein is large and thin. The umbilical artery forms a physiological helix around the umbilical vein. Three blood vessels pass through the length of the umbilical cord in spiral or coiled fashions. The spiral fusion of these umbilical blood vessels is called spiral course [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The umbilical cord helix is one of the crucial characteristics of the umbilical cord [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], as it protects and supports the blood vessels of the umbilical cord. The causes of umbilical coil formation are unknown, and these hypotheses include: active or passive torsion of the embryo, movement and rotation of the fetus along the long axis of the umbilical cord, disproportionate growth of umbilical blood vessels, fetal hemodynamics, and arrangement of muscle fibers in the umbilical artery wall [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The physiological coil of the umbilical cord spans approximately 6\u0026ndash;11 weeks with no adverse effects on the fetus. The UCT is formed if the umbilical cord coils for more than 11 weeks. The underlying mechanism of UCT remains unclear [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. It may be associated with umbilical cord dysplasia, the sporadic thickness of Wharton\u0026rsquo;s jelly, and excessive fetal movements [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The umbilical cord is rich in Wharton\u0026rsquo;s jelly, which comprises a substantial amount of collagen and elastic fibers, which can protect and support blood vessels, and prevent the umbilical cord from being compressed, ensuring continuous blood flow [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The weakness is often distorted and narrowed in the absence of Watton's jelly locally [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. UCT can cause twisting, narrowing, and occlusion of umbilical vessels, interruption of blood flow, and thrombosis [\u003cspan additionalcitationids=\"CR17\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. It can also result in chronic hypoxia with severely reduced blood flow, oligohydramnios, and fetal growth retardation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Complete blockade of the umbilical cord can also severely obstruct fetal-placental circulation with subsequent fetal death [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eHerein, UCI was used to assess the extent of UCT. UCI can directly indicate the number of weeks of UCT and indirectly indicate the density of the umbilical cord helix. UCI was measured by ultrasound before delivery because postpartum UCI lacks the segment of the umbilical cord closest to the fetus, which tends to be more twisted than the part near the placental insertion [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. In addition, antenatally the cord is more filled with blood, making the helix denser due to the intrinsic twist in the vessels [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. After the umbilical cord is severed postpartum, the blood in the umbilical cord decreases, the umbilical cord contracts and the umbilical cord helix becomes less dense than before birth. Prenatal diagnosis of UC currently has shortcomings. The diagnosis is often confirmed after birth [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe main condition in the group of stillbirth caused by UCT was as follows: the rate of older pregnant women was lower than that of pregnant women of appropriate age, and the rate of multiparawas lower than that of primipara. Unscheduled birth check-ups wereless compared to regular birth check-ups; and even regular birth check-ups could not prevent stillbirth, accounting for86.1%. The rate of stillbirth at 34\u0026ndash;40\u003csup\u003e+\u0026thinsp;2\u003c/sup\u003e weeks was the highest, reaching 47.2%. Pregnancy outcomes can be improved if such pregnant women can be timely admitted to a hospital and terminate their pregnancy.\u003c/p\u003e\u003cp\u003eResearch reports indicate that old age is associated with [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In the present study, the ratio of advanced age in the stillbirth group was lower than that in the live birth group; no significant correlation was noted between the two. Studies have reported a more relaxed abdominal wall of multipara and a wider uterine cavity, which is conducive to the free movement of the fetus and the formation of UCT [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The rate of multipara in the stillbirth group was lower than that in the live fetus group, and no significant correlation was noted between the two. Stillbirth can occur in pregnant women without regular birth check-ups. The rate of non-regular birth check-ups in the stillbirth group was higher than that in the live birth group; however, the two were not statistically significant. Regular prenatal check-ups cannot completely prevent the occurrence of stillbirth caused by UCT, and even stillbirth can occur within 3 days of prenatal examination, which is the current contradiction between doctors and patients. GDM is a key risk factor for UCT, which has a damaging effect on umbilical cord blood vessels and Wharton\u0026rsquo;s jelly [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The incidence of GDM in the stillbirth group was lower than that in the live birth group, and no significant correlation was noted between the two. No relevant studies have been found in previous literature, and the sample size needs to be expanded for further confirmation.\u003c/p\u003e\u003cp\u003eA few studies argue that male fetuses are active and more prone to UCT. Here, the rate of male fetuses in the stillbirth group was lower than that in the live fetus group, and no statistical difference was observed between the two groups. Notably, FGR is one of the most prevalent complications in obstetrics and is often associated with premature birth and stillbirth. This causes reduced placental circulation, and the fetus is in a state of inadequate nutrient supply and poor metabolism, hence hindering fetal growth and development, causing FGR [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Fetuses with FGR have slower growth and development, reduced compensatory capacity, and are more likely to be stillborn after UCT. Decreased or vanished fetal movement, and slow fetal heart rate are early warning signs of intrauterine abnormalities, which may be caused by abnormal fetal blood supply. In this case, reduced fetal movement occurs even if the umbilical artery blood flow is not fully blocked [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]; the next step is interrupted blood flow, which results in stillbirth. Herein, the incidence of reduced or absent fetal movement was significantly higher in the stillbirth group (61.1%) than in the live birth group (7.7%). Fetal movement can predict fetal distress or near death earlier than fetal heart rate. Fetal movement can be reduced to disappear, which may last a few days to approximately one week; however, it may also quickly disappear. Nevertheless, the interval between the disappearance of fetal movement and that of the fetal heart can be up to 12\u0026ndash;48 hours. The incidence of stillbirth reduces if the pregnancy is terminated when the fetal heart rate remains good. Therefore, when the fetal movement or the fetal heart rate is abnormal, the fetal situation should be first established, a timely ultrasound examination should be performed, and the umbilical cord should be carefully observed to improve the pregnancy outcome as far as possible.\u003c/p\u003e\u003cp\u003eAmniotic fluid is an indispensable substance in the uterus that ensures normal fetal development. UCT obstructs umbilical blood flow and decreases the circulation of the placenta; the fetal blood circulation is redistributed to maintain blood supply to the brain and heart, whereas the renal blood flow and the fetal urine production to be reduced, causing oligohydramnios, which also weakens the buffering effect of amniotic fluid. The periuterine pressure directly acts on the fetal body when the uterine wall is close to the fetus and the uterus contracts, increasing the chance of umbilical cord compression, thereby influencing the fetal placental circulation, and further causing fetal distress or even death. In the case of hydramnios, the fetus has more room for movement and is more active, making it easier to UCT [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. At the same time, UCT causes the umbilical cord to compress and narrow, thus obstructing the venous return, further causing increased leakage and hydramnios. Pilliod RA et al reported an increased incidence of stillbirth in pregnancies with hydramnios. Although the underlying cause is unknown, this will be the focus of future research [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eStudies have shown that excessively long cord is associated with [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. We found that the incidence of excessively long cords was lower in the stillbirth group than in the live fetus group; however, the two were not statistically significant. Univariate analysis revealed that the incidence of excessively short cording in the stillbirth group was higher than that in the live fetus group, whereas multivariate logistic regression showed no statistical difference. Further study should be conducted with larger sample sizes in the later stage. Studies have shown that a single umbilical artery is related to UCT [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The incidence of single umbilical artery was higher in the stillbirth group than in the live fetus group; however, there was no statistical significance between the two groups. It has been reported that when the umbilical cord is twisted\u0026thinsp;\u0026ge;\u0026thinsp;30 coils, the stillbirth rate is high. The rate of UCT\u0026thinsp;\u0026ge;\u0026thinsp;30 coils was higher in the stillbirth group than in the live fetus group; nonetheless, the two were not statistically significant. Torsion of the umbilical cord root at the umbilical chakra can result in cord root thinning and then cord-like necrosis, causing blood vessel occlusion or thrombosis, hence blocking the cord blood flow; the fetus eventually dies due to blood flow interruption. Other studies have revealed occurrences of intrauterine fetal death due to umbilical cord root torsion at the umbilical chakra [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTherefore, torsion location rather than the number of weeks is fundamental to the effect of UCT on the fetus. A careful examination of the umbilical cord in the umbilical chakra (where the umbilical cord enters the abdomen of the fetus) is necessary to prevent excessive twisting of the umbilical cord in such fetuses that could result in umbilical vessel blockage or even rupture. Besides, there is a need to identify the right time to terminate the pregnancy to prevent the risk of intrauterine fetal death [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eUnfortunately, UCT is considered unpredictable and unpreventable. It is mechanical with no effective therapy. The pregnancy must be promptly terminated when its torsion endangers the fetus.\u003c/p\u003e\u003cp\u003eThe missed diagnosis rates of ultrasound examination in the stillbirth group and the live fetus group were 91.7% and 90.2%, respectively. Ultrasound examination is the first choice for prenatal detection of UCT; however, the rate of missed diagnosis remains high.\u003c/p\u003e\u003cp\u003eThe main reasons for missed diagnosis of UCT in ultrasonography include: (1) Prenatal ultrasonography hardly displays the whole and complete umbilical cord [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], particularly in the third trimester due to the large gestational age and fetal occlusion; (2)Influenced by amniotic fluid volume, fetal position, anterior wall placenta, and abdominal wall fat layer of pregnant women, part of the umbilical cord is difficult to display, especially the umbilical cord root at the umbilical chakra. (3) After intrauterine death, the blood in the umbilical cord stagnates, and ultrasound examination of umbilical blood flow has no blood flow signal, and the difficulty of ultrasound observation of UCT increases. Thus, there is a need to continuously improve the scanning skills during the actual examination, and perform multi-section and multi-angle scanning, especially the umbilical root at the umbilical chakra to improve the accuracy of ultrasonic diagnosis of UCT.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eStrengths and limitations\u003c/h2\u003e\u003cp\u003eThis study is the first retrospective study with a large sample size to explore the high-risk factors of prenatal stillbirth caused by UCT and ultrasound examination. However, this study has some limitations as follows: (1) The stillbirth group (n\u0026thinsp;=\u0026thinsp;36) is much smaller than the live fetus group (n\u0026thinsp;=\u0026thinsp;388), which may affect the reliability of statistical comparisons, especially for rare outcomes. However, we included all positive cases during the study period without any loss in follow-up and exceeding the estimated sample size for sufficient representation. (2) Because of the retrospective nature, some interesting data might not be available or might be less reliable. (3) Although we excluded major confounding factors, such as medical conditions and multifetal pregnancies, other potential confounders; including socioeconomic background, cultural factors, and education, were not adjusted for in a multivariate analysis. Also, the effect of multiple pregnancies over time in the same women, which may influence the outcomes, was not considered for adjustment. (4) This is a single-center study involving cases from one hospital, the generalizability of our findings may be limited. But it could provide a foundation for future research. In the future, a multicenter, large-sample study should be conducted to validate our findings.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, prenatal birth caused by UCT is highly unpredictable, unpreventable, and unavoidable. Ultrasound is the preferred method for umbilical cord examination, and it is difficult to precisely diagnose UCT before delivery. Ultrasound doctors should therefore focus on observing the degree of umbilical cord helix in pregnant women with the above high-risk factors, particularly the umbilical cord root at the umbilical chakra particularly to improve the diagnosis of UCT. However, prenatal ultrasound hardly indicates the severity of UCT; therefore, the monitoring of fetal movement is paramount. For pregnant women with UCT detected before birth, prenatal care should be strengthened. Pregnant women should be informed without alarm, of potential adverse consequences. Most fetal vascular lumens do not show significant narrowing, and hemodynamics do not see significant changes even if the umbilical cord is twisted. Most fetuses can be normally delivered, without significant severe neonatal complications. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Nonetheless, such pregnant women need to be managed based on high-risk pregnancy. The fetal movement monitoring should also be strengthened to avoid missing the ideal time to see a doctor. Therefore, clinicians and sonographers should identify high-risk factors early, improve predictability and vigilance of UCT and its crises, and timely terminate pregnancy timely, to reduce the incidence of prenatal stillbirth.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eIVF-ET,\u0026nbsp;in vitro fertilization and embryo transfer\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eGDM,\u0026nbsp;gestational diabetes mellitus\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHDP,\u0026nbsp;hypertensive disorders of pregnancy\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFGR, fetal growth restriction\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUCT, umbilical cord torsion\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank the Staff at the department of ultrasound, obstetrics, and pediatrics for their technical assistances and facility supports.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eX.Z.W. contributed to conceptualization, proposal development, acquisition of data, data validation, data analysis，manuscript writing;\u0026nbsp;D. Z. and X.W.S.\u0026nbsp;contributed to acquisition of data, data validation，acquisition of\u0026nbsp;images, final approval;\u0026nbsp;X.Y.X.\u0026nbsp;contributed to data analysis, formal analysis，manuscript revision, fund support，final approval;\u0026nbsp;G.A.\u0026nbsp;contributed to data analysis, formal analysis,\u0026nbsp;manuscript revision,\u0026nbsp;final approval; All authors have read and agreed to the published version of the manuscript. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe\u0026nbsp;Key Research and Development Plan Projects in Hubei Province\u0026nbsp;(2022BCA041).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData from this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (Research ID:TJ-IRB202403027, Date of Approval 29 March 2024).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor details\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eDepartment of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan Hubei 430030, China. \u003csup\u003e2\u003c/sup\u003eDepartment of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan Hubei 430030, China.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKalem MN, Kalem Z, Akgun N. Yuce E, Aktas H. Investigation of possible maternal and fetal factors which affect umbilical coiling index. J Matern Fetal Neonatal Med. 2019;32(6):954-960. https://doi.org/10.1080/14767058.2017.1396311.Epub 2017 Nov 6.\u003c/li\u003e\n\u003cli\u003eFleisch MC，Hoehn T. Intrauterine fetal death after multiple umbilical cord torsion-complication of a twin pregnancy following assisted reproduction. J Assist Reprod Genet. 2008;25(6):277-279. https://doi.org/10.1007/s10815-008-9227-0. Epub 2008 Jun 26.\u003c/li\u003e\n\u003cli\u003eBen-Arie A, Weissman A, Steinberg Y, Levy R, Hagay Z. Oligohydramnios, intrauterine growth retardation, and fetal death due to umbilical cord torsion. Arch Gynecol Obstet. 1995;256 (3):159-61. https://doi.org/10.1007/BF01314645.\u003c/li\u003e\n\u003cli\u003eHammad IA, Blue NR, Allshouse AA, Silver RM, Gibbins KJ, Page JM, Goldenberg RL, Reddy UM, Saade GR, Dudley DJ, Thorsten VR, Conway DL, Pinar H, Pysher TJ. Umbilical cord abnormalities and stillbirth. Obstet Gynecol. 2020;135 (3): 644-652. https://doi.org/ 10.1097/ AOG.0000000000003676.\u003c/li\u003e\n\u003cli\u003eSong QY, Wen J, Luo H. Prenatal ultrasound findings regarding obstruction to blood flow and an umbilical artery varix caused by umbilical cord torsion. Eur J Obstet Gynecol Reprod Biol. 2022; 269:144-146. https://doi.org/10.1016/ j.ejogrb. 2021.12.014. Epub 2021 Dec 23.\u003c/li\u003e\n\u003cli\u003eBakotic BW, Boyd T, Poppiti R, Pflueger S. Recurrent umbilical cord torsion leading to fetal death in 3 subsequent pregnancies: a case report and review of the literature. Arch Pathol Lab Med. 2000;124 (9):1352-5. https://doi.org/10.5858/ 2000-124-1352-RUCTLT.\u003c/li\u003e\n\u003cli\u003eHashimoto S, Arakaki T, Takita H, Kaneko M, Matsuoka R, Sekizawa A. Prenatal diagnosis of the umbilical cord torsion at the placental cord insertion site: A case report and literature review. J Obstet Gynaecol Res. 2024;50 (9): 1728-1731. https://doi.org/10.1111/jog.16013. Epub 2024 Jul 2.\u003c/li\u003e\n\u003cli\u003eFleisch MC, Hoehn T. Intrauterine fetal death after multiple umbilical cord torsion-complication of a twin pregnancy following assisted reproduction. J Assist Reprod Genet. 2008; 25 (6):277-9. https://doi.org/10.1007/s10815-008-9227-0. Epub 2008 Jun 26.\u003c/li\u003e\n\u003cli\u003eHayes DJL, Warland J, Parast MM, et al. Umbilical cord characteristics and their association with adverse pregnancy outcomes: A systematic review and meta-analysis. PLoS One. 2020;15 (9): e0239630. https://doi.org/10.1371/ journal. pone.0239630. eCollection 2020.\u003c/li\u003e\n\u003cli\u003eChen RX, Yan JY, Han Q, Zheng LH. Factors related to morbidity and maternal and perinatal outcomes of umbilical cord torsion. J Int Med Res. 2020; 48 (3):300060520905421. https://doi.org/10.1177/0300060520905421.\u003c/li\u003e\n\u003cli\u003eStrong TH Jr, Jarles DL, Vega JS, Feldman DB. The umbilical coiling index. Am J Obstet Gynecol. 1994;170 (1 Pt 1):29\u0026ndash;32. https://doi.org/10.1080/14767050400028899.\u003c/li\u003e\n\u003cli\u003ePatil NS, Kulkarni SR, Lohitashwa R. Umbilical cord coiling index and perinatal outcome. J Clin Diagn Res. 2013;7 (8):1675-7. https://doi.org/ 10.7860/JCDR/2013/5135.3224.\u003c/li\u003e\n\u003cli\u003eLiang C, Xu YF. Analysis of factors associated with the umbilical cord pitch value by ultrasound measurement in late pregnancy. BMC Pregnancy Childbirth. 2023;23 (1):583. https://doi.org/10.1186/s12884-023-05894-x.\u003c/li\u003e\n\u003cli\u003eMa\u0026apos;ayeh M, McClennen E, Chamchad D, Geary M, Brest N, Gerson A. Hypercoiling of the umbilical cord in uncomplicated singleton pregnancies. J Perinat Med. 2018;46 (6):593-598. https://doi.org/10.1515/jpm-2017-0034.\u003c/li\u003e\n\u003cli\u003ede Laat MW, Franx A, Bots ML, Visser GH, Nikkels PG. Umbilical coiling index in normal and complicated pregnancies. Obstet Gynecol. 2006;107 (5):1049-55. https://doi.org/10.1097/01.AOG.0000209197.84185.15.\u003c/li\u003e\n\u003cli\u003eTian CF, Kang MH, Wu W, Fu LJ. Relationship between pitch value or S/D ratio of torsion of cord and fetal outcome. Prenat Diagn. 2010;30(5): 454\u0026ndash;458. https://doi.org/10.1002/pd.2499.\u003c/li\u003e\n\u003cli\u003eSilver RM, Varner MW, Reddy U, et al. Work-up of stillbirth: a review of the evidence. Am J Obstet Gynecol. 2007;196 (5):433-44. https://doi.org/ 10.1016/j.ajog.2006.11.041.\u003c/li\u003e\n\u003cli\u003eMachin GA, Ackerman J, Gilbert-Barness E. Abnormal umbilical cord coiling is associated with adverse perinatal outcomes. Pediatr Dev Pathol. 2000; (5): 462\u0026ndash;471. https://doi.org/10.1007/s100240010103.\u003c/li\u003e\n\u003cli\u003ede Laat MW, Franx A, van Alderen ED, et al. The umbilical coiling index, a review of the literature. J Matern Fetal Neonatal Med. 2005;17(2):93-100. https://doi.org/10.1080/14767050400028899.\u003c/li\u003e\n\u003cli\u003eEzimokhai M, Rizk DE, Thomas L. Maternal risk factors for abnormal vascular coiling of the umbilical cord. Am J Perinatol. 2000; 17 (8):441e5. https://doi.org/10.1055/s-2000-13452.\u003c/li\u003e\n\u003cli\u003eNajafi L, Abedini A, Kadivar M, et al. Gestational diabetes mellitus: the correlation between umbilical coiling index, and intrapartum as well as neonatal outcomes. J Diabetes Metab Disord. 2019;18(1):51-57. https://doi.org/ 10.1007/s40200-019-00389-z.eCollection 2019 Jun.\u003c/li\u003e\n\u003cli\u003eEzimokhai M, Rizk DE, Thomas L. Thomas. Abnormal vascular coiling of the umbilical cord in gestational diabetes mellitus. Arch Physiol Biochem. 2001;109(3):209e14. https://doi.org/10.1076/apab.109.3.209.11593.\u003c/li\u003e\n\u003cli\u003eChen N, Qiu L, Luo H. A case report of umbilical cord torsion: Abnormal hemodynamics of the umbilical artery assessed by ultrasound. Eur J Obstet Gynecol Reprod Biol. 2023;285 214-216. https://doi.org/ 10.1016/ j.ejogrb. 2023.04. 015. Epub 2023 Apr 19.\u003c/li\u003e\n\u003cli\u003ePilliod RA, Page JM, Burwick RM, Kaimal AJ, Cheng YW, Caughey AB. Caughey. The risk of fetal death in nonanomalous pregnancies affected by polyhydramnios. Am J Obstet Gynecol. 2015;213 (3): 410.e1-6. https://doi.org/ 10.1016 /j.ajog.2015.05.022. Epub 2015 May 14.\u003c/li\u003e\n\u003cli\u003ePredanic M, Perni SC, Chervenak FA. Antenatal umbilical coiling index and Doppler flow characteristics. Ultrasound Obstet Gynecol. 2006;28 (5): 699\u0026ndash;703. https://doi.org/10.1002/uog.2745.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"umbilical cord torsion, prenatal stillbirth, risk factors, ultrasound","lastPublishedDoi":"10.21203/rs.3.rs-6985153/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6985153/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eObjective\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThis study aims to investigate the high-risk factors and ultrasonic examination of prenatal stillbirth caused by umbilical cord torsion (UCT).\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethod\u003c/b\u003e\u003c/p\u003e\u003cp\u003eWe retrospectively analyzed the electronic data of 424 pregnant women with UCT who delivered from January 2013 to February 2024 in Tongji Hospital, Tongji Medical College, University of Science and Technology. The subjects were divided into a stillbirth group (36 cases) and a live fetus group (388 cases) based on fetal conditions. In addition, demographic data, clinical manifestations, pregnancy complications and comorbidities, abnormalities of the fetus and its appendages, ultrasound diagnosis, as well as other data of the two groups were collected. The risk factors of stillbirth caused by UCT were analyzed through univariate and multivariate logistic regression analyses.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e\u003cp\u003eMultiple Logistic regression analysis revealed that fetal growth restriction (FGR), history of decreased or vanished fetal movement, history of slow fetal heart rate, oligohydramnios, hydramnios, and umbilical cord root torsion at the umbilical chakra were independent risk factors for prenatal stillbirth caused by UCT (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, OR\u0026thinsp;\u0026gt;\u0026thinsp;1). Based on ultrasonic examination, the missed diagnosis rate of UCT in the stillbirth group was 91.7%.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e\u003cp\u003eHigh-risk factors for prenatal stillbirth caused by UCT include FGR, a history of decreased or vanished fetal movement, a history of slow fetal heart rate, oligohydramnios, hydramnios, and umbilical cord root torsion at the umbilical wheel. Prenatal stillbirth is related to the position of the UCT rather than the number of weeks. Prenatal ultrasound detects UCT at a low rate.\u003c/p\u003e","manuscriptTitle":"Clinical analysis of prenatal stillbirth caused by umbilical cord torsion","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-22 08:17:00","doi":"10.21203/rs.3.rs-6985153/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-08-08T05:19:56+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-02T19:10:55+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-02T14:14:05+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-27T07:58:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-22T15:32:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"246028413206643774608564774502963560154","date":"2025-07-20T02:05:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"258101307751810414641763637858043862598","date":"2025-07-18T15:43:53+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-16T08:45:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"296623553665558316897639995546107380717","date":"2025-07-16T08:37:52+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"281721761630322349311706389918269409860","date":"2025-07-16T00:48:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"242430413736330158040475218168940599292","date":"2025-07-15T07:43:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"312145102030729390672703772913141674312","date":"2025-07-15T06:54:24+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-15T01:45:41+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-06-27T05:45:11+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-26T22:43:02+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-06-26T22:41:56+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pregnancy and Childbirth","date":"2025-06-26T15:51:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"646231ec-663c-447f-a86a-f1a4318665af","owner":[],"postedDate":"July 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-12-15T16:00:45+00:00","versionOfRecord":{"articleIdentity":"rs-6985153","link":"https://doi.org/10.1186/s12884-025-08524-w","journal":{"identity":"bmc-pregnancy-and-childbirth","isVorOnly":false,"title":"BMC Pregnancy and Childbirth"},"publishedOn":"2025-12-10 15:57:16","publishedOnDateReadable":"December 10th, 2025"},"versionCreatedAt":"2025-07-22 08:17:00","video":"","vorDoi":"10.1186/s12884-025-08524-w","vorDoiUrl":"https://doi.org/10.1186/s12884-025-08524-w","workflowStages":[]},"version":"v1","identity":"rs-6985153","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6985153","identity":"rs-6985153","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}