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

INTRODUCTION: The aim of this study was to investigate the association between ovarian hyperstimulation syndrome (OHSS) and adverse pregnancy outcome. EVIDENCE ACQUISITION: 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. intrahepatic 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 intrauterine fetal death (IUD) and the individual components of both primary and secondary outcomes. EVIDENCE SYNTHESIS: Thirteen studies (3303 ART pregnancies with and 89,720 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.