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

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