Frozen-thawed embryo transfer is an independent risk factor for third stage of labor complications.

PURPOSE Third stage of labor complications are more prevalent following singleton vaginal deliveries of gestations conceived through in vitro fertilization (IVF) and fresh embryo transfer. This study aimed to evaluate these complications in pregnancies conceived through frozen-thawed embryo transfer (FET), in which endometrial preparation differs from fresh cycles. METHODS A cohort study of all singleton pregnancies conceived through IVF-FET who delivered vaginally at a tertiary medical center during 2007-2017. The study group consisted of 88 IVF-FET gestations (cases) that were matched to 176 spontaneous pregnancies based on age, gravidity, parity and gestational week at delivery (controls). The association between mode of conception and third stage of labor complication rate was examined. RESULTS Baseline characteristics were similar between groups, except for a lower prevalence of induction of labor in the control group (23.3% vs. 36.3%, p = 0.03). The rate of post-partum hemorrhage (PPH), manual lysis and revision of the uterine cavity were all higher in pregnancies conceived through IVF-FET versus spontaneously (13.6% vs. 5.7%, p = 0.018; 17% vs. 2.3%, p < 0.001; and 21.6% vs. 6.8%, p < 0.001, respectively). Multivariate analysis adjusting for age, previous cesarean section, induction of labor, neonatal weight and use of analgesia demonstrated that deliveries following IVF-FET were independently associated with an increased risk for third stage of labor complications (estimated OR = 3.45, p = 0.0002). CONCLUSION IVF-FET is an independent risk factor for PPH, need for manual lysis and revision of the uterine cavity. Precautionary measures should be undertaken in the third stage in deliveries following IVF-FET, even if no other risk factors are present.