Oral contraceptive pretreatment significantly reduces ongoing pregnancy likelihood in gonadotropin-releasing hormone antagonist cycles: an updated meta-analysis.

Ongoing pregnancy rate (PR) per randomized woman was found to be significantly lower in patients with oral contraceptive (OC) pill pretreatment (relative risk: 0.80, 95% confidence interval [CI]: 0.66-0.97; rate difference: -5%, 95% CI: -10% to -1%; fixed effects model) after pooling data from six randomized controlled trials encompassing 1,343 patients. Duration of stimulation (weighted mean difference [WMD]: +1.33 days, 95% CI: +0.61-2.05) and gonadotropin consumption (WMD: +360 IUs, 95% CI: +158-563) were significantly increased after OC pretreatment, but there was no statistically significant gain in the number of cumulus-oocyte complexes (WMD: +0.6 cumulus-oocyte complexes, 95% CI: -0.08-1.25).