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

To investigate the impact of a previous cesarean delivery on pregnancy outcomes of in vitro fertilization and frozen-thawed embryo transfer (FET). 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, =338), group B (single embryo transfer group with vaginal delivery history, =78), group C (double embryo transfer group with cesarean delivery history, =444), and group D (double embryo transfer group with vaginal delivery history, =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. (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 >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 <0.05). There were no statistically significant in miscarriage rate, preterm birth rate and neonatal birth weight between the two groups (all >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 >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), <0.01). (4) The occurrence of the low-birth-weight infant were related to gestational age (=0.41, 95%: 0.32-0.54) and twin pregnancy (=4.44, 95%: 1.93-10.21), and the occurrence of macrosomia was related to BMI (=1.18, 95%: 1.06-1.32). Moreover, the previous delivery method was not related to the neonatal birth weight (>0.05). 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.