[Effect of body mass index on the assisted reproductive outcome of frozen-thawed embryo transfer in patients with polycystic ovary syndrome]

Objective: To investigate the effect of body mass index (BMI) on clinical pregnancy and neonatal outcomes in patients with polycystic ovary syndrome (PCOS) during frozen-thawed embryo transfer. Methods: A total of 650 patients with PCOS who received routine in vitro fertilization or intracytoplasmic sperm injection treatment for frozen-thawed embryo transfer from June 2014 to June 2019 in Tianjin Central Hospital of Gynecology Obstetrics were retrospectively analyzed. According to BMI, PCOS patients were divided into group A (18.5≤BMI<23 kg/m², n=253), group B (23≤BMI<25 kg/m², n=167), and group C (BMI≥25 kg/m², n=230). The general information, clinical pregnancy outcomes, pregnancy complications, the incidence of macrosomia and low-birth-weight infants were compared in the three groups, and the influencing factors of neonatal birth weight were analyzed. Results: The embryo implantation rate, clinical pregnancy rate, and ongoing pregnancy rate all showed downward trend with the increase of BMI, but the differences were not statistically significant (all P>0.05). The live birth rate in group C [47.0% (108/230)] was significantly lower than those in groups A and B, with statistical significance (χ²=7.43, P=0.024). The late miscarriage rate was higher in group C [9.4% (13/139)] than in groups A and B (χ²=7.66, P=0.022). The birth rates of macrosomia in groups B [22.2% (16/72)] and group C [21.1% (16/76)] were significantly higher than that in group A, and the difference was statistically significant (χ²=14.15, P=0.001). There was no statistically significant difference in the incidence of gestational diabetes between the three groups (χ²=3.81, P=0.149). The incidence of hypertension disorders complicating pregnancy increased with the increase of BMI, and the difference was not statistically significant (P>0.05). Regression analysis showed that macrosomia was significantly associated with maternal pre-pregnancy BMI and gestational weeks, and the risk of macrosomia increased by 15% (95%CI: 3%-28%) for every increase in maternal BMI. Conclusions: The embryo implantation rate, clinical pregnancy rate, and ongoing pregnancy rate of PCOS patients in frozen-thawed embryo transfer cycles show downward trend with the increase of BMI. Obese patients with PCOS have a significant increase in late miscarriage rate and a significant decrease in live birth rate. The incidence of hypertension disorders complicating pregnancy in PCOS patients in the obese group has an increasing trend, and the birth rate of macrosomia has increased significantly. Therefore, it is recommended that obese women with PCOS lose weight scientifically before pregnancy to improve pregnancy and neonatal outcomes.

[Impact of previous cesarean delivery on pregnancy outcomes of in vitro fertilization and frozen-thawed embryo transfer]

Objective: To investigate the impact of a previous cesarean delivery on pregnancy outcomes of in vitro fertilization and frozen-thawed embryo transfer (FET). Methods: The clinical data of 1 179 patients who received in vitro fertilization and FET in Tianjin Central Hospital of Gynecology Obstetrics from January 2014 to May 2019 and had a history of the previous delivery were retrospectively analyzed. The patients were divided into four groups according to different previous delivery history and the number of embryo transferred: group A (single embryo transfer group with cesarean delivery history, n=338), group B (single embryo transfer group with vaginal delivery history, n=78), group C (double embryo transfer group with cesarean delivery history, n=444), and group D (double embryo transfer group with vaginal delivery history, n=319). The 1∶1 propensity score based on age, body mass index (BMI), infertility duration, basal FSH, basal LH, number of oocytes retrieved and high-quality embryo rate was used to match group A and B (caliper value=0.15), group C and D (caliper value=0.05), and group A and C (caliper value=0.01) respectively to reduce the influence of selection bias. The clinical pregnancy outcomes of patients were compared. Results: (1) Group A and group B were single embryo transfer groups with a total of 77 pairs of matched patients. There were no statistically significant differences in clinical pregnancy rate [42.9% (33/77) vs 45.5% (35/77)], miscarriage rate, preterm birth rate, and neonatal birth weight (all P>0.05). (2) Group C and group D were double embryo transfer groups with a total of 304 pairs of matched patients. The clinical pregnancy rate [42.4% (129/304)] and twin pregnancy rate [9.5% (29/304)] of Group C were significantly lower than those of Group D [53.0% (161/304), 15.5% (47/304) respectively; both P<0.05). There were no statistically significant in miscarriage rate, preterm birth rate and neonatal birth weight between the two groups (all P>0.05). (3) Groups A and C matched 318 pairs of patients. The two groups had no statistical significances in clinical pregnancy rate [38.4% (122/318) vs 45.6% (145/318)], miscarriage rate and preterm birth rate (all P>0.05), but the twin pregnancy rate in group C was significantly higher than that of group A [11.3% (36/318) vs 0.3% (1/318), P<0.01). (4) The occurrence of the low-birth-weight infant were related to gestational age (OR=0.41, 95%CI: 0.32-0.54) and twin pregnancy (OR=4.44, 95%CI: 1.93-10.21), and the occurrence of macrosomia was related to BMI (OR=1.18, 95%CI: 1.06-1.32). Moreover, the previous delivery method was not related to the neonatal birth weight (P>0.05). Conclusions: Patients with different delivery histories receive FET therapy, the pregnancy outcomes of single embryo transfer are not significantly different, and the success rate of double embryo transfer in patients with a cesarean delivery history is low. The neonatal birth weight is not related to the history of the cesarean section. It is recommended that patients with a cesarean delivery history choose elective single embryo transfer to ensure the success rate and to reduce the risk.