Risk factors associated with pregnancy outcomes in patients with recurrent pregnancy loss after treatment.

This retrospective cohort study included women in early pregnancy with a history of reproductive disorders, including infertility, recurrent chemical pregnancies, spontaneous abortions, and recurrent pregnancy loss, who received treatment at the Department of Obstetrics and Gynecology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, from June 2018 to June 2020. The inclusion criteria for participants were as follows: women aged 20–50 years, with a gestational age of < 12 weeks at their initial hospital visit, who have experienced more than two consecutive spontaneous abortions with the same sexual partner prior to 28 weeks of gestational age, and HCG ≥ 50 IU/L. The exclusion criteria were patients lacking weight and height data in the first trimester and couples without chromosome reports. Participant selection details are shown in Fig.  1 . After experiencing therapy for RPL, patients were monitored to track early miscarriage rates before 12 weeks and live birth outcomes. A total of 431 patients were included in this study, and pregnancy and live birth outcomes were followed up by a trained nurse through telephone calls. Fig. 1 Flowchart of the participant selection in this study Flowchart of the participant selection in this study Women were evaluated for thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPO-Ab), thyroglobulin antibody (TG-Ab), B lymphocytes, NK cells, antinuclear antibody, antithrombin III activity, platelet aggregation function, anti-cardiolipin antibody, lupus anticoagulant (LA), homocysteine (HCY), protein C (PC), protein S (PS), anti-β2 glycoprotein antibody, anti-phosphatidylserine antibody, and thromboelastogram: R-time, K-time, Angle, maximum amplitude (MA), elasticity platelet mapping (EPL) and clotting rime prolonged to 30 min (LV30). Blood glucose level (fasting plasma glucose, FPG, mmol/L) and insulin level (fasting insulin, FINS, µIU/ml) were recorded after fasting overnight for 12 h, HOMA-IR was calculated as: HOMA-IR = FPG*FINS/22.5. Women were treated according to the Chinese expert consensus on the diagnosis and treatment of recurrent abortion (the 2016 edition) [ 11 ]. Hyperthyroidism : for patients diagnosed with hyperthyroidism before pregnancy, it is recommended to stabilize the condition before attempting conception. Patients with mild hyperthyroidism can use propylthiouracil during pregnancy. Hypothyroidism : for patients diagnosed with hypothyroidism before pregnancy, thyroid hormone replacement therapy is necessary. After the thyroid function returns to normal, they should wait for three months before attempting conception, and continue using thyroid hormones throughout the pregnancy. Subclinical hypothyroidism : to maintain normal thyrotropin levels, our department practiced the appropriate use of thyroid hormones and iodine. Diabetes : for patients diagnosed with diabetes prior to pregnancy, discontinue hypoglycemic medications and switch to insulin therapy after achieving normal blood glucose levels. Plan for conception after a three-month period. Insulin resistance : insulin-sensitizing agents like metformin, in conjunction with nutritional counseling, are utilized to address insulin resistance. Obese , overweight , or underweight : collaborate with a nutritionist for weight management and nutritional guidance and intervention, establishing a multidisciplinary approach integrating nutrition with obstetrics and gynecology. Alloimmune dysfunction : The Korean Society for Reproductive Immunology guidelines [ 12 ] recommend intravenous immunoglobulin G (IVIG) for recurrent pregnancy loss (RPL) associated with cellular immune abnormalities. In cases of RPL with antiphospholipid antibody positivity or antiphospholipid syndrome, IVIG is indicated when heparin and/or aspirin use is contraindicated. To assess cellular immunological anomalies, the ratio of peripheral blood NK cells and NK cell cytotoxicity is advised. The criteria for IVIG therapy in our hospital included: elevated NK cell percentage; severe rheumatic immune disease with inadequate response to conventional treatment; severe antiphospholipid syndrome (APS) with ineffective response to conventional treatment; and exploratory treatment for unexplained recurrent spontaneous abortion. Administration protocols: intravenous infusion on the 8th to 10th day of the menstrual cycle during preconception; upon confirmation of successful pregnancy, an additional intravenous infusion should be promptly delivered, with a regimen of one course per week, generally continued until 10 to 12 weeks of gestation. It may be sustained for severe autoimmune disorders. Dosage: 400–500 mg/kg each administration, with 1–3 administrations per course contingent upon the exact circumstances. human immunoglobulin therapy is recommended for patients with RPL who exhibit an elevated number or heightened activity of NK cells after ruling out other contributing factors. According to prior studies [ 13 , 14 ], our institution defines a high percentage of NK cells as ≥ 12%. Positive antinuclear antibodies : for patients with recurrent miscarriages who test positive for antinuclear antibodies, a consultation with a rheumatologist is recommended. Adrenal cortical hormone therapy, specifically prednisone at a dosage of 10-20 mg daily, is advised for individuals with RPL who are positive for antinuclear antibodies. Prethrombotic state : clinical prethrombotic conditions include both congenital and acquired types: congenital prethrombotic conditions result from genetic variations associated with coagulation and fibrinolysis, including mutations in the Factor V and Factor II (prothrombin) genes, as well as deficiencies in protein S, protein C, and antithrombin III, among others. Acquired prethrombotic states primarily contain antiphospholipid syndrome (APS), acquired hyperhomocysteinemia, and several other conditions that induce a hypercoagulable state of blood. Currently, prevalent indicators applied to identify the prethrombotic state at our hospital involve anticardiolipin antibody (aCL), anti-beta2 glycoprotein 1 (β2GP1) antibody, lupus anticoagulant (LA), homocysteine (Hcy), protein C, protein S, and antithrombin III (AT-III). Patients in the early stages of pregnancy can receive low-molecular-weight heparin alone or with aspirin. Low molecular weight heparin is injected subcutaneously once or twice a day at 5000 IU. Treatment can begin early in pregnancy, usually when blood β-hCG testing confirms pregnancy. Before treatment ends, prethrombotic state markers must normalize. Treatment may last the entire pregnancy or be stopped 24 h before delivery. Low-dose aspirin (50–75 mg per day) is advised before pregnancy. Platelet count, coagulation function, and fibrinolysis should be monitored during treatment. Hyperhomocysteinemia : Patients assessed for hyperhomocysteinemia during early pregnancy may get treatment with either low molecular weight heparin alone or a combination of low molecular weight heparin and aspirin, in conjunction with folic acid and vitamin B12 therapy. Antiphospholipid syndrome : Thanks for your comments. According to the 2016 edition of the Chinese expert consensus on the diagnosis and treatment of recurrent abortion [ 11 ], and a study by Alijotas-Reig J et al. [ 15 ], there are two types of APS: typical and non-typical. A typical APS must have at least one clinical criterion, including three or more spontaneous abortions before the 10th week of pregnancy, one or more miscarriages after the 10th week, or one or more cases of placental insufficiency before the 34th week; at least one laboratory criterion, such as LA positivity, aCL, or anti-β2GP1 antibody (Ab) titers > 99th percentile, confirmed in two or more tests at least 12 weeks apart. The three primary antiphospholipid antibody spectrums (aPLs) are anti-β2GP1 Ab, LA, and aCL. In non-typical APS, the laboratory criteria for aPLs only meet low-titer positivity (95th-99th percentile) and do not meet high-titer positivity (> 99th percentile). Non-typical APS has the clinical features of typical APS but intermittently shows positive aPLs but lacks clinical manifestations (e.g., two unexplained miscarriages before the 10th week of gestation; three or more non-consecutive unexplained miscarriages). Low-dose aspirin (75 mg/day) may be used for persons with no history of miscarriage or one miscarriage before 10 weeks. After confirmation of pregnancy, 5,000 IU of heparin anticoagulant therapy may be given twice daily until delivery to patients with a history of RPL or one or more miscarriages after 10 weeks. Before pregnancy, RPL patients with thrombosis should start anticoagulant medication. Postpartum thrombosis is more likely within three months, hence anticoagulant therapy should be continued for 6–12 weeks. Those with a history of thrombosis may transition to warfarin. For patients with non-typical APS, individualized anticoagulant therapy should be administered. Parental karyotype abnormality : Homologous chromosomal robertsonian translocations prevent proper gamete production. Homologous chromosomal Robertsonian translocation carriers should utilize contraception to minimize miscarriages and malformed babies or consider egg or sperm donation for fertility concerns. Prenatal diagnosis is recommended for couples with autosomal balanced translocation and non-homologous chromosome Robertsonian translocation. Abnormalities of the uterus : Transcervical resection of adhesions is advised for individuals with uterine adhesions prior to pregnancy; nevertheless, the management of other congenital malformations of the genital tract remains controversial. Our institution adopts the FIGO classification for uterine leiomyomas, along with prior reviews [ 16 ], and the management protocols are as follows: Type 0 myomas are completely located within the uterine cavity, while type 1 myomas are less than 50% intramural. Hysteroscopic myomectomy is recommended for both type 0 and type 1 myomas, and GnRH agonists or mifepristone are utilized to cure anemia prior to surgery. Type 2: ≥ 50% intramural; Type 3: 100% intramural, in contact with the endometrium; Type 4: 100% intramural, no contact with endometrium or subserosa; Type 5: subserosal, ≥ 50% intramural; Type 6: subserosal, < 50% intramural; Type 7: pedunculated subserosal; Type 8: other (e.g., cervical, parasitic). For type 2 myomas or multiple myomas types 2 to 5 or myomas type 2–5, if the size exceeds 4–5 cm and distorts the uterine cavity, or if the myomas remain large due to great volume at baseline for in other types, myomectomy through laparoscopy, minilaparotomy, or hysteroscopy may be considered once hemoglobin levels are normalized. The American Fertility Society classifications for congenital anomalies of the genital tract were applied [ 17 ], and transcervical hysteroscopic resection of the septum was conducted under abdominal ultrasound guidance for patients with partial or complete septate uterus and arcuate uterus. For patients diagnosed with cervical insufficiency, preventative, emergency, or urgent cervical cerclage procedures could be considered depending on the patient’s condition, and preventative c ervical cerclage is performed at 13–14 weeks of pregnancy. Hyperthyroidism : for patients diagnosed with hyperthyroidism before pregnancy, it is recommended to stabilize the condition before attempting conception. Patients with mild hyperthyroidism can use propylthiouracil during pregnancy. Hypothyroidism : for patients diagnosed with hypothyroidism before pregnancy, thyroid hormone replacement therapy is necessary. After the thyroid function returns to normal, they should wait for three months before attempting conception, and continue using thyroid hormones throughout the pregnancy. Subclinical hypothyroidism : to maintain normal thyrotropin levels, our department practiced the appropriate use of thyroid hormones and iodine. Diabetes : for patients diagnosed with diabetes prior to pregnancy, discontinue hypoglycemic medications and switch to insulin therapy after achieving normal blood glucose levels. Plan for conception after a three-month period. Insulin resistance : insulin-sensitizing agents like metformin, in conjunction with nutritional counseling, are utilized to address insulin resistance. Obese , overweight , or underweight : collaborate with a nutritionist for weight management and nutritional guidance and intervention, establishing a multidisciplinary approach integrating nutrition with obstetrics and gynecology. Alloimmune dysfunction : The Korean Society for Reproductive Immunology guidelines [ 12 ] recommend intravenous immunoglobulin G (IVIG) for recurrent pregnancy loss (RPL) associated with cellular immune abnormalities. In cases of RPL with antiphospholipid antibody positivity or antiphospholipid syndrome, IVIG is indicated when heparin and/or aspirin use is contraindicated. To assess cellular immunological anomalies, the ratio of peripheral blood NK cells and NK cell cytotoxicity is advised. The criteria for IVIG therapy in our hospital included: elevated NK cell percentage; severe rheumatic immune disease with inadequate response to conventional treatment; severe antiphospholipid syndrome (APS) with ineffective response to conventional treatment; and exploratory treatment for unexplained recurrent spontaneous abortion. Administration protocols: intravenous infusion on the 8th to 10th day of the menstrual cycle during preconception; upon confirmation of successful pregnancy, an additional intravenous infusion should be promptly delivered, with a regimen of one course per week, generally continued until 10 to 12 weeks of gestation. It may be sustained for severe autoimmune disorders. Dosage: 400–500 mg/kg each administration, with 1–3 administrations per course contingent upon the exact circumstances. human immunoglobulin therapy is recommended for patients with RPL who exhibit an elevated number or heightened activity of NK cells after ruling out other contributing factors. According to prior studies [ 13 , 14 ], our institution defines a high percentage of NK cells as ≥ 12%. Positive antinuclear antibodies : for patients with recurrent miscarriages who test positive for antinuclear antibodies, a consultation with a rheumatologist is recommended. Adrenal cortical hormone therapy, specifically prednisone at a dosage of 10-20 mg daily, is advised for individuals with RPL who are positive for antinuclear antibodies. Prethrombotic state : clinical prethrombotic conditions include both congenital and acquired types: congenital prethrombotic conditions result from genetic variations associated with coagulation and fibrinolysis, including mutations in the Factor V and Factor II (prothrombin) genes, as well as deficiencies in protein S, protein C, and antithrombin III, among others. Acquired prethrombotic states primarily contain antiphospholipid syndrome (APS), acquired hyperhomocysteinemia, and several other conditions that induce a hypercoagulable state of blood. Currently, prevalent indicators applied to identify the prethrombotic state at our hospital involve anticardiolipin antibody (aCL), anti-beta2 glycoprotein 1 (β2GP1) antibody, lupus anticoagulant (LA), homocysteine (Hcy), protein C, protein S, and antithrombin III (AT-III). Patients in the early stages of pregnancy can receive low-molecular-weight heparin alone or with aspirin. Low molecular weight heparin is injected subcutaneously once or twice a day at 5000 IU. Treatment can begin early in pregnancy, usually when blood β-hCG testing confirms pregnancy. Before treatment ends, prethrombotic state markers must normalize. Treatment may last the entire pregnancy or be stopped 24 h before delivery. Low-dose aspirin (50–75 mg per day) is advised before pregnancy. Platelet count, coagulation function, and fibrinolysis should be monitored during treatment. Hyperhomocysteinemia : Patients assessed for hyperhomocysteinemia during early pregnancy may get treatment with either low molecular weight heparin alone or a combination of low molecular weight heparin and aspirin, in conjunction with folic acid and vitamin B12 therapy. Antiphospholipid syndrome : Thanks for your comments. According to the 2016 edition of the Chinese expert consensus on the diagnosis and treatment of recurrent abortion [ 11 ], and a study by Alijotas-Reig J et al. [ 15 ], there are two types of APS: typical and non-typical. A typical APS must have at least one clinical criterion, including three or more spontaneous abortions before the 10th week of pregnancy, one or more miscarriages after the 10th week, or one or more cases of placental insufficiency before the 34th week; at least one laboratory criterion, such as LA positivity, aCL, or anti-β2GP1 antibody (Ab) titers > 99th percentile, confirmed in two or more tests at least 12 weeks apart. The three primary antiphospholipid antibody spectrums (aPLs) are anti-β2GP1 Ab, LA, and aCL. In non-typical APS, the laboratory criteria for aPLs only meet low-titer positivity (95th-99th percentile) and do not meet high-titer positivity (> 99th percentile). Non-typical APS has the clinical features of typical APS but intermittently shows positive aPLs but lacks clinical manifestations (e.g., two unexplained miscarriages before the 10th week of gestation; three or more non-consecutive unexplained miscarriages). Low-dose aspirin (75 mg/day) may be used for persons with no history of miscarriage or one miscarriage before 10 weeks. After confirmation of pregnancy, 5,000 IU of heparin anticoagulant therapy may be given twice daily until delivery to patients with a history of RPL or one or more miscarriages after 10 weeks. Before pregnancy, RPL patients with thrombosis should start anticoagulant medication. Postpartum thrombosis is more likely within three months, hence anticoagulant therapy should be continued for 6–12 weeks. Those with a history of thrombosis may transition to warfarin. For patients with non-typical APS, individualized anticoagulant therapy should be administered. Parental karyotype abnormality : Homologous chromosomal robertsonian translocations prevent proper gamete production. Homologous chromosomal Robertsonian translocation carriers should utilize contraception to minimize miscarriages and malformed babies or consider egg or sperm donation for fertility concerns. Prenatal diagnosis is recommended for couples with autosomal balanced translocation and non-homologous chromosome Robertsonian translocation. Abnormalities of the uterus : Transcervical resection of adhesions is advised for individuals with uterine adhesions prior to pregnancy; nevertheless, the management of other congenital malformations of the genital tract remains controversial. Our institution adopts the FIGO classification for uterine leiomyomas, along with prior reviews [ 16 ], and the management protocols are as follows: Type 0 myomas are completely located within the uterine cavity, while type 1 myomas are less than 50% intramural. Hysteroscopic myomectomy is recommended for both type 0 and type 1 myomas, and GnRH agonists or mifepristone are utilized to cure anemia prior to surgery. Type 2: ≥ 50% intramural; Type 3: 100% intramural, in contact with the endometrium; Type 4: 100% intramural, no contact with endometrium or subserosa; Type 5: subserosal, ≥ 50% intramural; Type 6: subserosal, < 50% intramural; Type 7: pedunculated subserosal; Type 8: other (e.g., cervical, parasitic). For type 2 myomas or multiple myomas types 2 to 5 or myomas type 2–5, if the size exceeds 4–5 cm and distorts the uterine cavity, or if the myomas remain large due to great volume at baseline for in other types, myomectomy through laparoscopy, minilaparotomy, or hysteroscopy may be considered once hemoglobin levels are normalized. The American Fertility Society classifications for congenital anomalies of the genital tract were applied [ 17 ], and transcervical hysteroscopic resection of the septum was conducted under abdominal ultrasound guidance for patients with partial or complete septate uterus and arcuate uterus. For patients diagnosed with cervical insufficiency, preventative, emergency, or urgent cervical cerclage procedures could be considered depending on the patient’s condition, and preventative c ervical cerclage is performed at 13–14 weeks of pregnancy. SPSS software (version 29.0, IBM Corporation, USA) was used to analyze the data. Normally distributed continuous variable was recorded as the mean (standard deviation), while non-normally distributed data was documented as the median (interquartile range). Frequency data was presented as % (n). The t-test was utilized for comparing normally distributed data between groups, whereas the Mann–Whitney U test was applied for non-normally distributed data. The chi-square (χ²) test was used to compare qualitative data between groups. Univariate as well as multivariate logistic regression analysis were performed to evaluate the risk factors for pregnancies lasting ≥ 12 weeks and live birth outcomes.

Among the 431 patients with RPL included in the study, 313 achieved an ongoing pregnancy ≥ 12 weeks. Of these, 251 patients completed follow-up via phone, while 62 patients were lost to follow-up. Of the 251 patients who were followed up, 227 attained live births, whereas 24 experienced pregnancy loss at ≥ 12 weeks (Fig.  1 ). The ages of the women varied from 23 to 50 years, and the number of spontaneous abortions ranged from two to seven. The average BMI was 22.32 ± 3.11 kg/m². Among patients with uterine abnormalities, six individuals with myomas (types 1 to 6, sizes 0.5–8 cm) underwent myomectomy by laparoscopy, minilaparotomy, or hysteroscopy, while 14 patients with asymptomatic myomas recording less than 5 cm received no medical intervention. Additionally, 74 patients underwent transcervical resection of adhesions; seven patients with a septate uterus and two patients with an arcuate uterus had transcervical hysteroscopic resection of the septum; and three patients with cervical insufficiency underwent cervical cerclage surgery. Furthermore, one patient with a partly septate uterus, four patients with an arcuate uterus, two patients with an unicornuate uterus, and two patients with a didelphic uterus did not receive surgical treatments. The clinical characteristics of patients with and without ongoing pregnancy ≥ 12 weeks, as well as the outcomes of live births, are detailed in Tables  1 and 2 . No statistically significant differences were found in patients with and without ongoing pregnancy ≥ 12 weeks regarding number of miscarriages, BMI, TSH, TPO-Ab, TG-Ab, HOMA-IR, and parental karyotype abnormality. Compared with the group of women with ongoing pregnancy ≥ 12 weeks, the women in the group with pregnancy loss < 12 weeks were older (32.64 ± 5.08 vs. 31.54 ± 4.34, P  = 0.026), and with higher occurrence rate of uterine abnormalities (34.70% vs. 24.60%, P  = 0.035). Further investigation revealed a higher prevalence of uterine leiomyomas among women experiencing pregnancy loss < 12 weeks compared to those with ongoing pregnancies ≥ 12 weeks (9.30% vs. 2.9%, P  = 0.005) (Table  1 ). Additionally, no significant differences were present in patients with and without live birth regarding age, number of miscarriages, BMI, assisted reproductive technology pregnancy, abnormalities of the uterus, TSH, TPO-Ab, TG-Ab, HOMA-IR and parental karyotype abnormality (Table  2 ). Table 1 Comparison of clinical characteristics, uterine anatomical abnormalities, endocrine and genetic factors in patients with RPL across pregnancy outcomes Characteristic Pregnancy loss < 12 weeks ( n  = 118) Ongoing pregnancy ≥ 12 weeks ( n  = 313) P -value Age a , years 32.64 ± 5.08 31.54 ± 4.34 0.026 Number of miscarriages a , n 2.55 ± 0.84 2.54 ± 0.80 0.930 BMI a , kg/m 2 21.97 ± 3.24 22.46 ± 3.05 0.152 Assisted reproductive treatment b , % 14 (11.9) 45 (14.4) 0.499 Abnormalities of the uterus b , % 41 (34.70) 77 (24.60) 0.035  Arcuate uterus 0 (0.00) 6 (1.90) 0.292 d  Didelphic uterus 0 (0.00) 2 (0.60) 0.940 d  Septate uterus 4 (3.40) 4 (1.30) 0.295 d  Unicornuate uterus with a rudimentary horn 0 (0.00) 2 (0.60) 0.940 d  Intrauterine adhesion 24 (20.30) 50 (16.00) 0.284  Cervical incompetence 0 (0.00) 3 (1.00) 0.676 d  Uterine leiomyomas 11 (9.30) 9 (2.90) 0.005  Adenomyosis 2 (1.70) 1 (0.30) 0.378 TSH a , IU/ml 2.52 ± 1.33 2.34 ± 1.38 0.248 TPO-Ab c , IU/ml 106.00 (28.00-202.00) 83.50 (28.00-200.00) 0.330 TG-Ab c , IU/m 67.00 (21.00-134.00) 54.00 (18.75–173.00) 0.875 HOMA-IR a 1.99 ± 0.96 2.15 ± 1.23 0.221 Parental karyotype abnormality b , % 3 (2.50) 10 (3.20) 0.970 d  Inversion 1 (0.80) 5 (1.60) 0.895 d  Balanced reciprocal translocation 0 (0.00) 3 (1.00) 0.676 d  Robertsonian translocation 1 (0.80) 1 (0.30) 1.000 d  Chimera 1 (0.80) 1 (0.30) 1.000 d a Mean ± SD, b N(%), c median (interquartile range) d Data analyzed using continuity correction chi-square test Comparison of clinical characteristics, uterine anatomical abnormalities, endocrine and genetic factors in patients with RPL across pregnancy outcomes a Mean ± SD, b N(%), c median (interquartile range) d Data analyzed using continuity correction chi-square test Table 2 Comparison of clinical characteristics, uterine anatomical abnormalities, endocrine and genetic factors in women with RPL across live birth outcomes Characteristic Live birth ( n  = 227) Non-live birth ( n  = 24) P -value Age a , y 31.39 ± 4.37 32.33 ± 4.78 0.321 Number of miscarriages a , n 2.58 ± 0.84 2.58 ± 0.93 0.973 BMI a , kg/m 2 22.05 ± 3.11 21.43 ± 2.77 0.352 Assisted reproductive treatment b , % 30 (13.20) 4 (16.70) 0.876 Abnormalities of the uterus b , % 49 (21.60) 6 (25.60) 0.701  Arcuate uterus 4 (1.80) 0 (0.00) 1.000 d  Uterus duplex 0 (0.00) 0 (0.00) -  Septate uterus 1 (0.40) 1 (4.20) 0.456 d  Unicornuate uterus, 2 (0.90) 0 (0.00) 1.000 d  Intrauterine adhesion 34 (15.00) 3 (12.50) 0.982  Cervical incompetence 1 (0.40) 0 (0.00) 1.000 d  Uterine leiomyomas 7 (3.10) 2 (8.30) 0.460 d  Adenomyosis 0 (0.00) 0 (0.00) - TSH a , mU/L 2.29 ± 1.25 2.27 ± 0.81 0.458 TPO-Ab c , IU/ml 69.00 (28.00-176.00) 130.00 (28.00-222.00) 0.624 TG-Ab c , IU/ml 46.50 (17.00-158.25) 82.00 (24.00-170.00) 0.532 HOMA-IR 2.23 ± 1.32 1.98 ± 0.81 0.179 Parental karyotype abnormality b , % 5 (2.20) 2 (8.30) 0.279  Inversion 2 (0.90) 1 (4.20) 0.674 d  Balanced reciprocal translocation 2 (0.90) 0 (0.00) 1.000 d  Robertsonian translocation 1 (0.40) 1 (4.20) 0.456 d  Chimera 0 (0.00) 0 (0.00) - a Mean ± SD, b N(%), c median (interquartile range) d Data analyzed using continuity correction chi-square test Comparison of clinical characteristics, uterine anatomical abnormalities, endocrine and genetic factors in women with RPL across live birth outcomes a Mean ± SD, b N(%), c median (interquartile range) d Data analyzed using continuity correction chi-square test There were no significant differences in B lymphocyte, NK cells, antinuclear antibody, antithrombin III activity, platelet aggregation function, anticardiolipin antibody IgA, anticardiolipin antibody IgM, anticardiolipin antibody IgG, lupus anticoagulant, homocysteine, PC, PS, anti-β2 glycoprotein antibody IgA, anti-β2 glycoprotein antibody IgM, anti-β2 glycoprotein antibody IgG, anti-phosphatidylserine IgG, anti-phosphatidylserine IgM and thromboelastogram (R-time, K-time, Angle, MA, EPL and LV 30) between the groups of patients with and without ongoing pregnancy ≥ 12 weeks and live birth, details were outlined in Tables  3 and 4 . Table 3 Comparison of immunological and prothrombotic state factors in patients with RPL across pregnancy outcomes Characteristic Pregnancy loss < 12 weeks ( n  = 118) Ongoing pregnancy ≥ 12 weeks ( n  = 313) P -value B lymphocyte a , % 15.19 ± 4.32 14.95 ± 4.41 0.676 NK cells a , % 11.41 ± 6.07 13.35 ± 8.16 0.052 Antinuclear antibody a , S/CO 1.33 ± 0.79 1.26 ± 0.85 0.569 Antithrombin III activity a , % 90.13 ± 11.62 90.91 ± 12.85 0.576 Platelet aggregation function a , % 42.22 ± 5.63 42.30 ± 6.09 0.245 Anticardiolipin antibody IgA a , CU 1.75 ± 0.65 1.95 ± 1.37 0.131 Anticardiolipin antibody IgM a , CU 2.51 ± 1.51 2.79 ± 2.65 0.973 Anticardiolipin antibody IgG a , CU 5.13 ± 3.27 5.14 ± 4.81 0.288 Lupus anticoagulant 34.16 ± 3.73 34.00 ± 3.01 0.658 Homocysteine a , umol/L 6.83 ± 1.03 6.61 ± 1.08 0.063 PC a , % 94.70 ± 19.60 96.87 ± 21.10 0.417 PS a , % 72.63 ± 21.14 71.83 ± 22.36 0.719 Anti-β2 glycoprotein antibody IgA a , CU 3.89 ± 0.54 3.97 ± 0.78 0.404 Anti-β2 glycoprotein antibody IgM b , CU 1.10 (1.10–1.58) 1.10 (1.10–1.50) 0.504 Anti-β 2 glycoprotein antibody IgG b , CU 7.28 ± 4.41 7.18 ± 3.33 0.847 Anti-phosphatidylserine IgG a , U/ml 9.83 ± 1.78 10.76 ± 9.12 0.296 Anti-phosphatidylserine IgM a , U/ml 15.45 ± 9.05 15.00 ± 8.07 0.633 R-time a , minute 6.02 ± 1.06 5.95 ± 1.19 0.576 K-time a , minute 1.61 ± 0.36 1.63 ± 0.48 0.785 Angle a , degree 67.32 ± 4.31 67.24 ± 5.35 0.887 MA a , mm 60.20 ± 4.36 60.66 ± 5.04 0.394 EPL b , % 0.10 (0.10–1.63) 0.10 (0.10–1.40) 0.646 LV 30 b , % 0.10 (0.10–0.20) 0.10 (0.10–0.20) 0.822 a Mean ± SD, b median (interquartile range) Comparison of immunological and prothrombotic state factors in patients with RPL across pregnancy outcomes a Mean ± SD, b median (interquartile range) Table 4 Comparison of immunological and prothrombotic state factors in women with RPL across live birth outcome Characteristic Live birth ( n  = 227) Non-live birth ( n  = 24) P -value B lymphocyte a , % 14.81 ± 4.36 15.22 ± 3.27 0.701 NK cells a , % 13.09 ± 7.11 10.25 ± 5.78 0.114 Antinuclear antibody a , S/CO 1.16 ± 0.78 1.52 ± 0.98 0.172 Antithrombin III activity a , % 91.18 ± 12.97 90.61 ± 10.31 0.834 Platelet aggregation function a , % 43.18 ± 6.10 41.00 ± 6.35 0.105 Anticardiolipin antibody IgA a , CU 2.00 ± 1.26 1.95 ± 1.00 0.858 Anticardiolipin antibody IgM a , CU 2.86 ± 2.81 2.80 ± 1.39 0.920 Anticardiolipin antibody IgG a , CU 4.63 ± 3.09 5.63 ± 3.69 0.149 Lupus anticoagulant 35.05 ± 4.22 34.04 ± 3.04 0.141 Homocysteine a , umol/L 6.70 ± 1.19 6.95 ± 1.11 0.333 PC a , % 96.64 ± 21.07 92.50 ± 24.28 0.483 PS a , % 73.09 ± 22.36 67.09 ± 15.00 0.324 Anti-β2 glycoprotein antibody IgA a , CU 3.92 ± 0.71 3.66 ± 0.96 0.175 Anti-β2 glycoprotein antibody IgM b , CU 1.10 (1.10–1.58) 1.10 (01.10–1.90) 0.538 Anti-β 2 glycoprotein antibody IgG a , CU 7.24 ± 3.84 6.05 ± 2.48 0.217 Anti-phosphatidylserine IgG a , U/ml, 10.82 ± 10.42 10.42 ± 2.98 0.854 Anti-phosphatidylserine IgM a , U/ml 15.47 ± 8.60 14.30 ± 6.93 0.529 R-time a , minute 5.91 ± 1.21 6.15 ± 1.29 0.353 K-time a , minute 1.61 ± 0.46 1.72 ± 0.43 0.257 Angle a , degree 67.46 ± 5.30 66.25 ± 4.93 0.283 MA a , mm 60.58 ± 4.92 59.78 ± 4.33 0.446 EPL b , % 0.10 (0.10–1.40) 0.10 (0.10–0.10) 0.096 LV 30 b , % 0.10 (0.10–0.15) 0.10 (0.10–0.10) 0.078 Comparison of immunological and prothrombotic state factors in women with RPL across live birth outcome Univariate logistic regression analysis, as presented in Supplementary Table 1 , included factors analyzed in Tables  1 and 3 . Factors that significantly differed ( P  < 0.05) were included in multivariate logistic regression analysis: female age and abnormalities of the uterus. According to the data shown in Table  5 , female age exhibited a significant association with the risk of pregnancy loss < 12 weeks (adjusted OR: 1.48 [95% CI: 1.05 to 2.07], P  = 0.025). Uterine abnormalities were linked to a 1.7-fold increased risk of pregnancy loss < 12 weeks compared to those without uterine abnormalities (adjusted OR:1.78 [95% CI] 1.11 to 2.79, P  = 0.016). Table 5 Multivariate logistic regression analysis results for risk factors associated with pregnancy loss < 12 weeks Adjusted OR (95%CI) P - value Female age 1.48 (1.05 to 2.07) 0.025 Abnormalities of the uterus 1.78 (1.11 to 2.79) 0.016 Multivariate logistic regression analysis results for risk factors associated with pregnancy loss < 12 weeks Univariate logistic regression, detailed in Supplementary Table 2 , included factors analyzed in the Tables  2 and 4 . Factors that marginally significant differed ( P  < 0.1) were included for multivariate logistic regression analysis: parental karyotype abnormality, NK cells, platelet aggregation function, anti-β2 glycoprotein antibody IgA, anti-β2 glycoprotein antibody IgG, EPL, and LV30. As indicated in Table  6 , parental karyotype abnormalities were associated with an 8% higher risk of non-live births compared to those without parental karyotype abnormalities (adjusted OR:0.08 [95% CI 0.01 to 0.76], P  = 0.029). Table 6 Multivariate logistic regression analysis results for risk factors associated with live birth outcomes( P  < 0.2) Adjusted OR (95%CI) P - value Parental karyotype abnormalities 0.08 (0.01 to 0.76) 0.029 NK cells - 0.189 Platelet aggregation function - 0.487 Anti-β2 glycoprotein antibody IgA - 0.532 Anti-β 2 glycoprotein antibody IgG - 0.277 EPL - 0.696 LV30 - 0.840 Multivariate logistic regression analysis results for risk factors associated with live birth outcomes( P  < 0.2)

Recurrent pregnancy loss (RPL), also known as recurrent spontaneous abortion or recurrent miscarriage, affects approximately 1–2% of all fertile couples [ 1 ]. There are varying definitions of RPL worldwide. The American Society for Reproductive Medicine (ASRM) guideline of 2020 defines RPL as the spontaneous loss of two or more pregnancies from conception to 24 weeks [ 2 ]. The updated European Society of Human Reproduction and Embryology (ESHRE) guideline of 2022 adopted this definition [ 1 ]. In the 2023 Royal College of Obstetricians and Gynaecologists (RCOG) guideline, the criterion of “three or more consecutive first-trimester miscarriages” is utilized for RPL definition [ 3 ]. Overall, RPL can be caused by many different conditions, the common risk factors include maternal and paternal age, number of previous miscarriages, race, life style, thrombophilia, genetic factors, uterine anomalies, and endocrine disorders [ 3 ]. Specifically, the increased incidence of female age-related aneuploidy is the greatest determinant of RPL [ 4 ]. Additionally, obesity is also a risk factor for RPL; the maternal body mass index (BMI) of women with a history of RPL was significantly higher than that of women without RPL [ 5 ]. Thirdly, antiphospholipid antibody (particularly anticardiolipin antibodies, and/or lupus anticoagulant antibodies, and/or anti–2-glycoprotein I antibodies) syndrome is significantly associated with RPL [ 6 ]. Relevant genetic factors for RPL mainly include genetic mutations, genetic polymorphisms, chromosomal variants, and chromosomal polymorphisms. Embryonic chromosomal abnormalities account for 29–60% of cases in RPL couples [ 7 ]. The prevalence of anatomical uterine anomalies in women experiencing RPL varies from 15 to 42%, with septate uterus being the congenital malformation most commonly associated with RPL. Other uterine anomalies (unicornuate, arcuate, and bicornuate uteri) are reported in only 0.5–2% of RPL patients [ 8 ]. Endocrine disorders significantly correlated with RPL include positive anti-thyroid peroxidase antibody [ 9 ]. In recent years, the treatment for RPL has been addressed in international guidelines, the main treatment methods are listed as follows [ 10 ]: preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS) can be used in the management of RPL caused by genetic factors; surgical correction of significant anatomical uterine defects should be considered for RPL caused by anatomical factors; cervical cerclage is a method of choice for the cases of cervical weakness; low-dose aspirin plus heparin should be considered for women with antiphospholipid syndrome; levothyroxine, metformin, and bromocriptine can be used in the management of hypothyroidism, PCOS, and hyperprolactinemia in women with RPL. However, limited studies focus on the risk factors associated with pregnancy and live birth outcomes of patients with RPL who have undergone treatment. This study retrospectively identified risk factors associated with pregnancy and live birth outcomes following RPL therapy, considering factors such as uterine abnormalities, endocrine and immune disorders, genetic factors, and thrombophilia. We aimed to provide risk assessment information for pregnancy loss in patients with RPL after treatment, guide appropriate diagnosis and treatment for women of reproductive age, reduce the incidence of spontaneous miscarriage, and alleviate the economic and psychological burden on patients.

In conclusion, following treatment for recurrent pregnancy loss (RPL), age and uterine abnormalities have been identified as significant factors associated with pregnancy outcomes, while parental karyotype abnormalities have emerged as independent risks affecting live birth rates. Based on this evidence, managing patients with RPL after treatment should emphasize monitoring maternal age, addressing uterine abnormalities, and evaluating parental karyotypes. Advocating for timely fertility care in women of child-bearing age is essential. Special attention should be given to identifying and managing uterine abnormalities, with surgical intervention considered when indicated. Additionally, genetic counseling remains a cornerstone of care for individuals with chromosomal abnormalities, guiding personalized approaches to improving live birth outcomes.

This retrospective study involved 431 patients with RPL and conducted a comprehensive analysis of variations in uterine abnormalities, endocrine, genetic, immunological, and prothrombotic state factors among women with and without pregnancy loss < 12 weeks and live births after receiving treatment for thyroid and alloimmune dysfunction, diabetes, insulin resistance, prethrombotic conditions, hyperhomocysteinemia, antiphospholipid syndrome, cervical insufficiency, and other abnormalities. Our data revealed that women with RPL experiencing pregnancy loss < 12 weeks were older compared to those with ongoing pregnancies ≥ 12 weeks. Furthermore, multivariate logistic regression analysis highlighted maternal age as an independent risk factor affecting ongoing pregnancies ≥ 12 weeks. This association is primarily attributed to the increased likelihood of aneuploidy and fetal chromosomal abnormalities with advancing age [ 18 – 20 ]. Numerous studies have confirmed a significant correlation between advanced maternal age and adverse pregnancy outcomes [ 21 – 23 ]. A recent innovative study suggested that recurrent miscarriage and age-related disorders may share a common etiology, including cardiometabolic conditions. Implementing proactive interventions to reduce the risk of cardiovascular complications associated with pregnancy is crucial for safeguarding maternal and child health [ 24 ]. Furthermore, our data indicated that uterine abnormalities were independent risk factors affecting ongoing pregnancy ≥ 12 weeks. Uterine leiomyomas were generally considered to cause RPL [ 25 , 26 ]. Estrogen and progesterone stimulate the growth of leiomyomas. Currently, available medical treatments for leiomyomas focus on inhibiting estrogen or progesterone production or function; however, tumors often resume growth once the treatment is discontinued [ 25 ]. Uterine leiomyoma stem cells may enhance tumor growth through the paracrine activation of WNT/β-catenin pathway [ 27 ]. In our study, six persons with myomas (types 1 to 6, sizes 0.5–8 cm) underwent myomectomy, of them, three individuals achieved pregnancy ongoing pregnancy ≥ 12 weeks and two individuals received live birth. The American Society for Reproductive Medicine recommends the removal of cavity-distorting myomas in asymptomatic patients to potentially improve fertility and/or decrease the risk of miscarriage [ 28 ]. To date, although surgical management of uterine anomalies may not be proven effective for RPLs, it should be considered in certain cases to improve pregnancy outcomes. Surgical management of RPLs focuses on uterine anomalies like septa, intrauterine adhesions, and submucosal myomas [ 8 ]. Parental karyotype abnormalities are recognized as a significant factor contributing to RPL [ 29 ]. Consistent with previous studies [ 30 , 31 ], this study identified chromosomal abnormality as a significant risk factor influencing live birth outcomes. Previous studies have indicated a correlation between parental chromosomal alterations and advanced maternal age [ 32 ]. The incidence of chromosomal abnormalities in couples with RPL ranges from 3 to 8%, mainly including numerical and structural chromosomal anomalies [ 7 , 33 ]. As we know, performing preimplantation genetic testing has been proposed to improve the live birth rate for patients with chromosomal abnormalities [ 34 ]. However, in recent years, some studies suggested the opposite views. Shinichiro Ikuma et al. showed that PGD did not improve live birth rates in patients with RPL associated with chromosomal translocation [ 35 ]. Li S et al. evaluated the impact of parental abnormal chromosomal karyotypes on pregnancy outcomes in couples with RPL. Their study indicated abnormal karyotypes had a significant lower first pregnancy live birth rate, PGD for parental chromosomal abnormalities did not show improvement in the cumulative live birth rate but but significantly reduced the miscarriage rate [ 36 ]. Consequently, we recommend that parental karyotyping should be regarded as a critical component of routine evaluation for patients with RPL. Furthermore, patients identified with chromosomal abnormalities should receive enhanced prenatal monitoring and tailored management strategies to optimize pregnancy outcomes. Limited studies have delved into the risk factors influencing pregnancy and live birth outcomes following treatment for RPL. Our study has addressed this gap in current research, offering new evidence and insights into RPL treatment. Additionally, our findings hold significant implications for enhancing the management of patients with RPL both pre-pregnancy and during gestation. However, this study is constrained by the absence of data regarding infection status, the health condition of male partners, and the psychological well-being of the patients. Furthermore, given its retrospective nature, future research would benefit from high-quality, prospective, and randomized controlled trials to more effectively validate the impact of these risk factors.

Below is the link to the electronic supplementary material. Supplementary Material 1 Supplementary Material 1