Ovarian hyperstimulation syndrome and adverse pregnancy outcome: a systematic review and meta-analysis

Purpose of the article To investigate the association between ovarian hyperstimulation syndrome (OHSS) and adverse pregnancy outcome. Material and methods Medline, Embase and Cochrane databases were searched. The primary outcome was a composite score of adverse maternal outcome including either preterm birth (PTB), gestational diabetes mellitus (GDM), pre-eclampsia (PE) or pregnancy induced hypertension, intra-hepatic cholestasis of pregnancy, thromboembolic events or need for caesarean section (CS). Secondary outcomes were a composite score of adverse fetal outcome including either miscarriage, low birthweight, fetal anomalies or intra-uterine fetal death (IUD) and the individual components of both primary and secondary outcomes. Results 13 studies (3303 ART pregnancies with and 89720 without OHSS) were included. The risk of composite adverse maternal outcome (RR: 8.8, 95% CI 8.1-9.5) was higher in women with compared to those without OHSS. The association between OHSS and adverse pregnancy outcome was mainly due to the higher risk of PTB (RR: 11.4, 95% CI 10.5-12.4), while there was no difference in the risk of others primary outcome. Likewise, the risk of composite fetal outcome was higher in pregnancies with a prior OHSS (RR: 1.5, 95% CI 1.1-2.0). The strength of association between OHSS and composite adverse maternal outcome persisted when considering singleton pregnancies or those with severe disease. Conclusions Pregnancies complicated by OHSS are at high risk of adverse pregnancy outcome, especially PTB.