The association between polycystic ovary syndrome and ectopic pregnancy after in vitro fertilization and embryo transfer

We sought to assess the association between polycystic ovary syndrome (PCOS) and ectopic pregnancy after in vitro fertilization-embryo transfer (ET).

In this retrospective cohort study, we included 5339 women who had clinical pregnancies after in vitro fertilization treatment (PCOS, 205 women; non-PCOS, 5134 women) at Nanjing Medical University (China) between 2007 and 2011. Fresh and cryo-thawed ET cycles were analyzed respectively. The primary outcome measure was the occurrence of ectopic pregnancy. Multivariate logistic regression analysis was used to adjust for important confounders.

In fresh ET cycles of women who were undergoing controlled ovarian hyperstimulation (COH; n = 3303), women with PCOS had 3.06 times higher risk of ectopic pregnancy compared with those without PCOS (7.0% vs 2.4%; adjusted odds ratio [aOR], 3.06; 95% confidence interval [CI], 1.34-6.96). In the stratified analysis, for women without PCOS, the high estradiol group (>4085 pg/mL) had higher ectopic pregnancy rates compared with the low estradiol group (≤4085 pg/mL; 3.4% vs 2.0%; aOR, 1.99; 95% CI, 1.19-3.35); however, for women with PCOS, both high and low estradiol groups had high ectopic pregnancy rates (5.6% vs 7.7%; aOR, 0.92; 95% CI, 0.15-5.67). In cryo-thawed ET cycles without COH (n = 2036), the ectopic rates between women with and without PCOS were similar (2.2% vs 2.0%; aOR, 0.94; 95% CI, 0.22-4.07).

PCOS was associated with an increased risk of ectopic pregnancy after COH in fresh ET cycles, but not in cryo-thawed ET cycles. A possible explanation is that, compared with women without PCOS, women with PCOS appear to hold a lower threshold of hyperphysiologic estradiol level that triggers the occurrence of ectopic pregnancy after COH.