The impact of composite maternal & fetal ultrasound assessment on the mode of delivery in large-for-gestational-age fetuses: the Macrodia Trial

The impact of composite maternal & fetal ultrasound assessment on the mode of delivery in large-for-gestational-age fetuses: the Macrodia Trial | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 22 January 2026 V1 Latest version Share on The impact of composite maternal & fetal ultrasound assessment on the mode of delivery in large-for-gestational-age fetuses: the Macrodia Trial Authors : Carbone Ilma Floriana 0000-0002-5508-0947 [email protected] , Rasha KAMEL , Francesca M.P. GIGLI , Valentina ROMAGNOLI , Shaimaa S. YOUSEF , Rana Abdella , Ibrahim F. IBRAHIM , Enrico Iurlaro , Vittorio PARODI , Giovanna Esposito 0000-0001-7894-4456 , and Enrico Ferrazzi Authors Info & Affiliations https://doi.org/10.22541/au.176905277.79893747/v1 109 views 77 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Objective: To evaluate determinants of unplanned operative delivery in large-for-gestational-age fetuses. Design : Prospective, non-randomized, multicenter study. Setting: Hospital-based. Population or Sample: Singleton pregnancies with estimated fetal weight (EFW) and/or abdominal circumference (AC) >80 th . Methods: According to protocol, early induction of labor was scheduled when EFW and/or AC >95 th or when EFW and/or AC between 80 th and 95 th with unfavorable maternal indices. Otherwise, expectant management was planned. Proportion of unplanned operative delivery was compared between groups managed per protocol. Women were categorized according to early induction or expectant management in accordance with, or in deviation from, the protocol. The EFW to subpubic angle ratio (EFW/SPA) and the head circumference to subpubic angle ratio (HC/SPA) were evaluated by ROC analysis, and adjusted relative risk (RR) for unplanned operative delivery were estimated using Poisson regression. Main Outcome Measures: Unplanned operative delivery (vacuum-assisted or cesarean section). Results: Of the 223 patients included, 127 were managed per protocol (102 early induction, 25 expectant), while 96 were managed at clinicians’ discretion. Unplanned operative deliveries were more frequent among women induced per protocol than among those managed expectantly (52.9% vs. 12.0%; p<0.01). Short stature, obesity, narrow SPA, and fetal biometry were associated with unplanned operative delivery. In multivariable analysis, EFW/SPA ratio ≥34.78 (RR=1.71) and HC/SPA ratio ≥3.30 (RR=1.39) - the optimal ROC-derived cut-offs - were associated with a higher risk of unplanned operative delivery. Conclusions: Unplanned operative delivery was associated with unfavorable fetal biometry/maternal-subpubic-angle ratios, which may help identify women at higher risk, supporting individualized delivery management. The impact of composite maternal & fetal ultrasound assessment on the mode of delivery in large-for-gestational-age fetuses: the Macrodia Trial Ilma F. CARBONE, MD, PhD 1 ; Rasha KAMEL, MD 2 ; Francesca M.P. GIGLI, MD 3 ; Valentina ROMAGNOLI, MD 3 ; Shaimaa S. YOUSEF, MD 4 ; Rana M. ABDELLA, MD 2 ; Ibrahim F. IBRAHIM. MD, PhD 2 ; Enrico IURLARO, MD 1 ; Vittorio PARODI, MD 3 ; Giovanna ESPOSITO, PhD 3,5 ; Enrico M. FERRAZZI, MD 1,6 1 Unit of Obstetrics, Department of Mother and Child Area, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Mangiagalli Center, Milan, Italy 2 Department of Obstetrics & Gynecology, Maternal-Fetal Medicine unit, Cairo University, Cairo, Egypt 3 Department of Clinical Sciences and Community Health, Dipartimento di Eccellenza 2023-2027, University of Milan, Italy 4 Department of Obstetrics & Gynecology, Nasser specialized hospital, ElQualiobia, Egypt 5 Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy 6 Research Center for Fetal Maternal and Neonatal Medicine, Department of Clinical and Community Sciences, University of Milan Corresponding author: Running Title: Unplanned operative delivery in large-for-gestational-age fetuses Abbreviations : AUC, Area Under the Curve; BMI, Body Mass Index; CI, confidence interval; EFW, Estimated Fetal Weight; HC, Head Circumference; IQR, Interquartile Range; LGA, Large for Gestational Age; ROC, Receiver Operating Curve; RR, Relative Risk; SD, Standard Deviation; SPA, Subpubic Angle. ABSTRACT Objective: To evaluate determinants of unplanned operative delivery in large-for-gestational-age fetuses. Design : Prospective, non-randomized, multicenter study. Setting: Hospital-based. Population or Sample: S ingleton pregnancies with estimated fetal weight (EFW) and/or abdominal circumference (AC) >80 th . Methods: According to protocol, early induction of labor was scheduled when EFW and/or AC >95 th or when EFW and/or AC between 80 th and 95 th with unfavorable maternal indices. Otherwise, expectant management was planned. Proportion of unplanned operative delivery was compared between groups managed per protocol. Women were categorized according to early induction or expectant management in accordance with, or in deviation from, the protocol. The EFW to subpubic angle ratio (EFW/SPA) and the head circumference to subpubic angle ratio (HC/SPA) were evaluated by ROC analysis, and adjusted relative risk (RR) for unplanned operative delivery were estimated using Poisson regression. Main Outcome Measures: Unplanned operative delivery (vacuum-assisted or cesarean section). Results: Of the 223 patients included, 127 were managed per protocol (102 early induction, 25 expectant), while 96 were managed at clinicians’ discretion. Unplanned operative deliveries were more frequent among women induced per protocol than among those managed expectantly (52.9% vs. 12.0%; p<0.01). Short stature, obesity, narrow SPA, and fetal biometry were associated with unplanned operative delivery. In multivariable analysis, EFW/SPA ratio ≥34.78 (RR=1.71) and HC/SPA ratio ≥3.30 (RR=1.39) - the optimal ROC-derived cut-offs - were associated with a higher risk of unplanned operative delivery. Conclusions: Unplanned operative delivery was associated with unfavorable fetal biometry/maternal-subpubic-angle ratios, which may help identify women at higher risk, supporting individualized delivery management. Funding: This research was partially supported by Italian Ministry of Health, but did not receive any grant from, commercial, or for-profit sectors. Keywords: fetal macrosomia, estimated fetal weight, fetal head circumference, ultrasound pelvimetry, subpubic angle, unplanned operative delivery, induction of labor. INTRODUCTION Fetal macrosomia, an increasing condition that occurs in 8-10 percent of pregnancies, 1 is associated with an augmented composite maternal and infant morbidity. 2,3 Recent safe obstetrical practice has adopted the strategy to try “prevent” these risks by early induction of labor, or even in selected cases, by elective cesarean section. This strategy is not evidence-based and further trials were suggested by the recent Cochrane review on “suspected fetal macrosomia”. However, this systematic review concluded that in the induction of labour group, shoulder dystocia or fetal birth injuries (bone fractures) were reduced in babies over 4000g. 4 Maternal complications are similarly associated with macrosomia as reported by the updated metanalysis of Pergialiotis and co-workers, 5 and the reported analysis of Fuchs and co-workers, 6 among many other published studies. 1-3 In the absence of robust evidence-based procedures, clinical decision in each patient is mostly left to personal opinions and preferences, or local pragmatic protocols. Notwithstanding these clinical uncertainties, the mode of delivery is recommended be discussed with pregnant women with estimated fetal weight (EFW) ≥4000gr, 4 or around the 95 th percentile of full-term fetal growth charts. 7,8 This counselling was found to be better started at 36 weeks of gestation as suggested by a recent systematic review of predictive models of Cesarean Birth. 9 Ultrasound imaging, despite intrinsic reproducibility limitations, provide important information on fetal biometry and weight estimation at near term, both as universal screening or case finding in obese, diabetic or women with abnormal symphysis-fundal height. 10-15 While fetal head circumference (HC) was proved to be associated with the risk of unplanned intervention at the second stage of labor. 16,17 Fetal estimated growth and maternal height were also reported as significant parameters in many predictive models for cesarean birth. 9,18 Recently, the importance of the size of maternal pelvis was revisited due to the emerging role of the subpubic angle (SPA) as a new sonographic index. A narrow SPA requires that the fetal head, deflects and changes its descent direction from downwards to front and upwards. The fetal head would subsequently articulate its occiput with the pubic bones instead of under the pubic synchondrosis, thereby overstretching the perineal floor, and thus increasing both the need for stronger maternal pushing and the risk of lacerations ( Figure 1 ). This distance can be demonstrated by measuring the symphysis to head distance by ultrasound. 19-21 A narrow SPA might be also related to a narrow inter-ischiatic spine diameter which is typical for the android pelvis. This might cause a more difficult internal rotation at midpelvis. Youssef et al. in 2016, and Ghi et al. in 2018 reported an increased risk of operative vaginal delivery and/or emergency caesarean section in labor with a SPA < 100°, both in uncomplicated pregnancies and in case of large-for-gestational-age fetuses, for the frequent persistence of posterior occiput positions. 22,23 This ultrasound parameter proved to be independently associated with a higher risk of unplanned operative delivery and cesarean section. 24 An integrated assessment of HC and SPA could identify a subset of women at higher risk of unplanned operative delivery during labor, for whom early planned delivery might be beneficial. We hypothesized that screening at 35-37 weeks of gestation, 9 and subsequent case detection of large fetuses by a composite of ultrasound parameters combining fetal HC and the EFW (the passenger) with maternal variables (the passage) that might influence the mode of delivery, including maternal height and maternal SPA estimation by 3D ultrasound, could allow for the identification of pregnant women who could benefit from induction of labor at early term in a population at high risk of fetopelvic disproportion. The main objective of this study was to assess the risk of unplanned operative delivery in patients undergoing early induction of labor, according to maternal and fetal characteristics as defined by the study protocol, versus expectant management. The secondary objective was to evaluate in the whole cohort, independently from trial assignments to early induction or expectant management, how maternal and fetal parameters interact to influence the risk of unplanned operative delivery. MATERIALS AND METHODS Study design, setting and population This was a prospective, non-randomized, multicenter study carried out between September 2022 and September 2023 at the Unit of Obstetrics and Maternal Fetal Medicine of the Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico in Milan (EC 935_2022bis) and at the Department of Obstetrics & Gynecology of Cairo University (OT1201032023). Enrolment took place between 35 and 37 weeks of gestation at our outpatient maternal-fetal screening clinics for late pregnancy complications. Women aged 18 years or older with a singleton pregnancy, not affected by gestational diabetes, and with an EFW and/or abdominal circumference (AC) above the 80 th percentile were eligible for this study (n=276). Patients with at least one of the following criteria were excluded: planned caesarean section for fetal macrosomia according to ACOG guidelines, or for maternal request of cesarean section prior to labor (n=32). Two hundred and forty-four pregnant women were scheduled for their next outpatient visit at 38 weeks to confirm the sonographic fetal biometry and the EFW according to the standard Hadlock formula, and to assess the maternal SPA using a 3D trans-perineal ultrasound (Figure 2). Per protocol, early induction of labor was scheduled between 38 weeks +4 days and 39 weeks +4 days in the case of an EFW and/or AC > 95 th percentile as an isolated criterion, or in the case of an EFW and/or AC between the 80 th and 95 th percentile in addition to at least one of the following unfavorable indices: maternal height < 155 cm and/or SPA < 100° and/or, when available, obstetric conjugate < 11. The 80 th percentile was chosen based on the best estimate of weekly growth of large fetuses of 178 gr as reported by Cochrane systematic review on induction of labor. 4 Expectant management was therefore scheduled for women with an EFW and/or AC between the 80 th and 95 th percentile and none of the other above-mentioned unfavorable indices, until spontaneous labor ensued, or induction of labor was carried out at 41 weeks +2/+4 days. Twenty-one women were additionally excluded from the analysis as they underwent caesarean section in the first stage of labor due to cardiotocographic monitoring with repeated decelerations of concern with abnormal baseline (n=21). 25 Finally, 223 women were eligible for the analysis of the present study. Figure 3 shows the flowchart from enrolment of eligible cases to the recruitment for this study according to the management. During the study period, due to the known lack of universally agreed upon quality evidence on the best management of suspected macrosomic fetuses, it was left up to the discretion of the attending obstetricians, in their patient-by-patient management, to violate the study protocol and also up to the women’s orientation and desire. At the end of the trial, this real-life scenario constituted two additional interesting groups of women who either should had been induced per protocol, but underwent an expectant management, and vice versa a group of women who should had been included in the expectant management but were induced at early term. For each patient included in the study, the following data were collected on an electronic database: maternal demographic characteristics (i.e., age, height, weight, body mass index, parity, ethnicity), ultrasound fetal and maternal measurements (i.e., HC, EFW according to the standard Hadlock formula, 26 maternal SPA measured by a trans-perineal 3-D volume acquisition and offline reconstruction), mode of labor and delivery, gestational age, and birthweight. This set of data allowed to measure and estimate the relationship between the passenger (the fetus) and the passage (the maternal pelvis) by calculating the estimated fetal weight to subpubic angle ratio (EFW/SPA), and the head circumference to subpubic angle ratio (HC/SPA). Statistical analysis Descriptive statistics were used to summarize selected characteristics of the study sample. Categorical variables were expressed as absolute frequencies and percentages, and the chi-square test or Fisher’s exact test was used to assess differences in their distribution across comparison groups, as appropriate. Continuous variables were expressed as medians and interquartile ranges (IQR), and group differences were evaluated using the Mann–Whitney U test. The proportions of unplanned operative delivery (vacuum-assisted or cesarean section) were compared between groups defined by management per protocol (i.e., early induction at 38 weeks +4 days and 39 weeks +4 days, or expectant management). Comparisons were made between (i) women induced per protocol and women who were induced at early term without criteria, and (ii) women managed expectantly per protocol and women who should have been induced per protocol but were managed expectantly. Furthermore, women who should have been induced according to protocol but underwent expectant management were compared with those induced per protocol and women who should have been managed expectantly according to protocol but underwent early induction were compared with those managed expectantly per protocol. According to the secondary objective, the area under the receiver operating curve (ROC) was calculated to assess the diagnostic accuracy of the two considered parameters (i.e., EFW/SPA and HC/SPA ratios) in predicting unplanned operative delivery, considering the whole cohort regardless the management per protocol or violation. The optimal cut-off of the two ratios was defined according to Youden index. Poisson regression with a robust error variance was fitted to estimate the crude and adjusted relative risk (RR) and 95% confidence interval (CI) of unplanned operative birth according to EFW/SPA ratio and HC/SPA ratio (in categories, i.e., lower than or equal to/higher than the optimal cut-off). Adjusted model included terms for center, maternal age and height, parity, gestational age, and induction of labor (at any gestational age). All statistical analyses were conducted using SAS version 9.4 and R version 4.3.1. Of the 223 patients included in the study, 127 were managed according to the trial protocol: 102 were inducted at 38 weeks +4 days and 39 weeks +4 days and 25 received expectant management. In the absence of evidence based national or international guidelines on the management of LGA, 96 cases were treated by the staff on duty according to their best option and according to patient’s choice after informed counselling. Table 1 reports the comparison of maternal and fetal data and perinatal outcomes according to the management per protocol. As expected from the protocol criteria, women in the early induction group were significantly shorter, had a higher BMI at birth and a narrower SPA compared to those in the expectant management group. The EFW/SPA and HC/SPA ratios were both higher in the early induction group compared to the expectant management group. The proportion of unplanned operative deliveries was significantly higher in women who underwent early induction of labor than in the expectant management group (52.9% versus 12.0%; p<0.01). No neonates had Apgar scores below 5 at 5 minutes. Table 2 provides two comparisons of maternal and fetal data and perinatal outcomes. In the first comparison, we found that women with criteria for early induction who were induced per protocol (n=102) had a higher proportion of unplanned operative deliveries than those who were induced at early term without unfavorable parameters (n=44) (52.9% versus 27.3%, p<0.01). In the second comparison, we found that women who should have been induced per protocol but underwent expectant management (n=52) had a significantly higher proportion of unplanned operative deliveries compared to women who underwent expectant management per protocol (n=25), (59.6% versus 12.0%; p<0.01). It should be noted that in the latter group of 52 women with unfavorable parameters, managed expectantly in violation of protocol, 36 women eventually underwent induction at late term. Table 2 reports data that allowed additional comparisons. No significant difference was observed in the frequency of unplanned operative delivery between women managed expectantly who met criteria for early induction, and those properly induced per protocol (59.6% versus 52.9%; p=0.43). Similarly, no significant difference in proportion of unplanned operative delivery between women induced without meeting the criteria for induction, and those properly assigned to expectant management per protocol (27.3% versus 12.0%; p=0.14). Figure 4 shows the distribution of EFW/SPA and HC/SPA ratios according to mode of delivery observed in the whole cohort of 223 women. The median EFW/SPA and HC/SPA ratios were significantly lower in the uneventful vaginal birth group than in the unplanned operative birth group. The median (IQR) EFW/SPA was 33.1 (31.0-35.3) and 36.6 (34.0-41.8) in the two groups, respectively (p<0.01). The median (IQR) HC/SPA was 3.1 (2.9-3.3) and 3.3 (3.1-3.7) in the two groups, respectively (p<0.01). Birth weights were similar for large babies born after uneventful vaginal delivery and unplanned operative delivery, with median weights of 3710 g and 3728 g, respectively (p=0.77). Figure 5 shows the ROC curves for unplanned operative delivery according to these two ratios. The area under the curve for the EFW/SPA ratio was 0.75, while that for the HC/SPA ratio was 0.72, suggesting a moderate discriminatory ability. The optimal cut-off for the first ratio was found to be 34.78, while the optimal cut-off for the second ratio was 3.30. Table 3 shows the RR of unplanned operative delivery according to EFW/SPA and HC/SPA ratios. The risk of unplanned operative birth based on the optimal cut-off was about 2-folds and 1.5-folds higher, respectively in women with an EFW/SPA ratio equal to or higher than 34.78 and with a HC/SPA ratio equal to or more than 3.30. Adjusting the model for potential confounders, this risk decreased but remained significant. DISCUSSION Main findings This prospective study found that women with fetuses with an estimated weight in the upper end of normal percentiles, in between the 80 th and the 95 th percentile and unfavorable maternal indices, such as short stature and/or narrow SPA, who underwent early induction at term per protocol had an increased frequency of unplanned operative delivery compared to women with similar fetal parameters without other unfavorable maternal indices who were managed expectantly. These findings reinforce the importance of considering maternal anatomical and anthropometric characteristics in addition to EFW when planning delivery in pregnancies with fetuses in the upper end of normal weight percentiles. The absence of a significant difference in unplanned operative delivery rates between women induced without meeting the protocol criteria for early induction, and those properly managed expectantly suggests that fetal size alone in this borderline area of weight percentile, in the absence of unfavorable maternal indices, may not be a sufficient justification for early induction. Clinically, these findings suggest that fetuses in the 80 th to 95 th percentile are not at increased risk of unplanned operative delivery solely due to their suspected large size, supporting the safety of expectant management until late term in these cases. The lack of a significant difference between women meeting criteria for early induction who were induced and those who were not, further supports the idea that the elevated risk of operative delivery in these cases characterized by maternal low stature and narrow SPA, reflects the underlying intrinsic maternal-fetal profile rather than the management. Accordingly, regardless of per protocol allocation or protocol deviations, in the whole eligible cohort, both the EWF/SPA and HC/SPA ratios were significantly higher in those cases who underwent an unplanned operative delivery. When evaluated for their predictive value in unplanned operative delivery, these ratios demonstrated moderate discriminatory ability. Strength and Limitations As expected in this clinical trial, based on a new hypothesis in an area of clinical practice uncertainty, violations of study protocol were met based on attending medical staff in charge of its application and on patients’ preferences. A major limitation of the study is the potential for selection bias due to these deviations from the proposed protocol, particularly given the non-randomized design. Although the primary analysis focused on women who were managed according to the protocol to reduce potential confounding factors, almost half of the study population did not strictly adhere to the assigned management strategy. To mitigate this, the analysis was expanded to include women who deviated from the protocol, enabling comparison across four subgroups defined by adherence and risk criteria. This broader approach enhances the generalizability of the findings and reflects variability in real-world clinical decision-making. Nevertheless, residual confounding factors remain, and the results should be interpreted with caution. The secondary analysis examined how maternal and fetal parameters interacted with the risk of an unplanned operative delivery across the entire cohort, regardless of the assigned management strategy. However, as these parameters directly guide clinical decision-making, the analysis is subject to indication bias, which limits causal inference. Moreover, the optimal cut-off values identified by ROC analysis were derived and tested within the same population, which may limit the generalizability of the findings. To validate these findings and fully elucidate the independent effects of maternal and fetal characteristics on delivery outcomes, future prospective studies are needed, ideally randomized or conducted in settings where these parameters do not determine management. Interpretation The association of large babies and increased risk of operative delivery and fetal complications is a well know clinical issue. Recent data from the large Big Baby Trial in UK observed a reduction of shoulder dystocia in LGA fetuses with EFW above the 90 th percentile when induced per protocol 38+0 weeks’ gestation and 38+4 weeks’ gestation. In that large multicenter study, only the EFW had been considered the criteria for induction to be compared with standard of care. 27 Indeed, arrest or delayed progression in active second stage in large babies with possible maternal and fetal complications is a multifactorial phenomenon. Our results confirm that the SPA is one of these co-factors in agreement with data reported by Ghi et. al and Youssef et al., 22,23 who observed that a SPA narrower than 100° was correlated with the mode of delivery, especially in LGA fetuses. Rizzo et. al already explored the performance of a model integrating fetal HC, SPA and other maternal characteristics in predicting the need for an unplanned operative delivery, but they considered these as independent parameters. 24 In our trial we explored the relationship between EFW and HC, in fetuses at the upper end of normal percentile, with SPA. In the whole cohort, regardless of whether women were treated according to protocol or not, these ratios were significantly higher in women who had an unplanned operative birth compared with those who had an unplanned vaginal birth. When this angle is too narrow, the occiput of the fetus needs to be pushed lower down the pelvis by maternal efforts (Figure 1), so that the fetal occiput eventually can engage under the branches of pubic bones, not under the symphysis as in normal pelvis, to reach the point of leverage that makes the maternal expulsive forces deflect the head and change its direction form downward to front-ward and then crowning upward. 28 This occurs at the cost of a longer active second stage and overstretching of the pelvic floor muscle with subsequent pelvic floor dysfunctions. With advancing maternal age at first delivery the relevance of this pelvic parameter will become of major importance. According to the data reported by Morino, Ishihara et al. during pregnancy in young women, both the anterior and posterior width of the pelvis is increased by two and one centimeters respectively. 29 This well know pelvic plasticity, is significantly limited on the average after 30 years of age according to Waltenberger et al. who studied the age dependent changes in pelvic shape during adulthood. 30 This potential limitation associated with maternal age is further increased by the association between maternal age, obesity, metabolic syndrome and large fetuses. The study confirmed the hypothesized association between maternal and fetal parameters as variables that, when employed compositely, can independently predict mode of delivery in macrosomic fetuses, highlighting the predictive value of EFW/SPA and HC/SPA ratios. Personalized delivery management of large babies, based on these additional indices, may reduce unplanned operative deliveries when considered within the related clinical context. Future studies are needed aiming to validate our findings in diverse populations and aiming to refine the cut-off values of the explored ratios for predicting the mode of delivery in with fetuses in the upper end of normal weight percentiles CONCLUSION Women with with fetuses between the 80 th and 95 th percentile of estimated weight and unfavorable maternal height and pelvic parameters, who were induced at term had an increased risk of unplanned operative delivery compared with women with fetuses of similar size without other unfavorable maternal indices who were managed expectantly. These fetuses, in absence of maternal unfavorable indices could safely undergo an expectant management until late term without an increased risk of unplanned operative deliveries. The possible importance of the predictive role of fetal dimension-to-maternal pelvic parameters ratios was additionally confirmed by their comparison in the whole cohort, including cases in violation of protocol, that confirmed the significant difference between these ratios in women who underwent an unplanned operative delivery versus those who delivered vaginally without operative interventions. Authors’ contributions I.F.C., E.M.F., R.K., E.I. conceived the present idea and supervision the study. I.F.C., E.M.F., R.K. wrote the manuscript (draft and revisions). F.M.P.G. and V.R. contributed to writing (revisions) and interpretation of findings. F.M.P.G., V.R., V.P., R.M.A., I.F.I., and S.S.Y. contribute to data collection and analysis. G.E. performed statistical analysis. Presentation Findings were presented at ISLANDS Congress (International Study Group of labor and delivery sonography), Madrid, January 24-25, 2025. Declaration of competing interests The authors declare that they have no competing interests with any financial organization regarding the material discussed in the manuscript. Ethics Statement An informed consent for publication according to the Ethical Committee approval was signed by each patient. Data Availability Statement The datasets used and/or analysed during the current study are available upon reasonable request. References 1. Macrosomia: ACOG Practice Bulletin, Number 216. Obstet Gynecol. 2020;135(1):e18-e35. 2. Beta J, Khan N, Khalil A, Fiolna M, Ramadan G, Akolekar R. Maternal and neonatal complications of fetal macrosomia: systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2019;54(3):308-318. 3. Weissmann-Brenner A, Simchen MJ, Zilberberg E, et al. Maternal and neonatal outcomes of macrosomic pregnancies. Med Sci Monit. 2012;18(9):PH77-81. 4. Boulvain M, Thornton JG. Induction of labour at or near term for suspected fetal macrosomia. 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Supplementary Material File (2.table1.docx) Download 16.93 KB File (3.table2.docx) Download 18.65 KB File (4.table3.docx) Download 15.19 KB File (5.figure legend.docx) Download 20.30 KB Information & Authors Information Version history V1 Version 1 22 January 2026 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords delivery: assisted vaginal general obstetrics labour: induction Authors Affiliations Carbone Ilma Floriana 0000-0002-5508-0947 [email protected] Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Dipartimento di Area Materno Infantile View all articles by this author Rasha KAMEL Cairo University Department of Gynecology & Obstetrics View all articles by this author Francesca M.P. GIGLI Universita degli Studi di Milano Dipartimento di Scienze Cliniche e di Comunita View all articles by this author Valentina ROMAGNOLI Universita degli Studi di Milano Dipartimento di Scienze Cliniche e di Comunita View all articles by this author Shaimaa S. YOUSEF Nasser specialized hospital View all articles by this author Rana Abdella Cairo University Department of Gynecology & Obstetrics View all articles by this author Ibrahim F. IBRAHIM Cairo University Department of Gynecology & Obstetrics View all articles by this author Enrico Iurlaro Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Dipartimento di Area Materno Infantile View all articles by this author Vittorio PARODI Universita degli Studi di Milano Dipartimento di Scienze Cliniche e di Comunita View all articles by this author Giovanna Esposito 0000-0001-7894-4456 Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Dipartimento di Area Materno Infantile View all articles by this author Enrico Ferrazzi Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Dipartimento di Area Materno Infantile View all articles by this author Metrics & Citations Metrics Article Usage 109 views 77 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Carbone Ilma Floriana, Rasha KAMEL, Francesca M.P. GIGLI, et al. The impact of composite maternal & fetal ultrasound assessment on the mode of delivery in large-for-gestational-age fetuses: the Macrodia Trial. Authorea . 22 January 2026. DOI: https://doi.org/10.22541/au.176905277.79893747/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . 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