Is the probability of pregnancy after ovarian stimulation for IVF associated with serum estradiol levels on the day of triggering final oocyte maturation with hCG? A systematic review and meta-analysis.

PURPOSE The objective of this systematic review and metaanalysis was to examine if the probability of pregnancy after ovarian stimulation for in vitro fertilization (IVF), using GnRH analogues and gonadotrophins is associated with serum estradiol level (E2) on the day of triggering final oocyte maturation with human chorionic gonadotrophin (hCG). METHODS Twenty-one studies were eligible for this systematic review, including 19,598 IVF cycles, whereas three studies were eligible for metaanalysis, including 641 IVF cycles. The main outcome measure was achievement of ongoing pregnancy/live birth and, if not available, clinical pregnancy or biochemical pregnancy. RESULTS Pooling of data showed no differences in the probability of clinical pregnancy between patients with high and low E2 levels on the day of triggering final oocyte maturation. The pooled effect sizes for the E2 thresholds groups constructed, regarding clinical pregnancy were 2000-3000 pg/mL-OR 0.91, 95% CI 0.55 to 1.50, (fair quality/moderate risk of bias, n = 1 study), 3000-4000 pg/mL-OR 0.89, 95% CI 0.46 to 1.70, (fair quality/moderate risk of bias, n = 1 study, good quality/no information on which to base a judgement about risk of bias n = 2 studies), 4000-5000 pg/mL-OR 0.74, 95% CI 0.37 to 1.49 fair quality/moderate risk of bias, n = 1 study), 5000-6000 pg/mL-OR 0.62, 95% CI 0.19 to 1.98, (fair quality/moderate risk of bias, n = 1 study). In addition, no difference was observed in the probability of ongoing pregnancy for the E2 threshold group of 3000-4000 pg/mL OR 0.85, 95% CI 0.40 to 1.81(good quality/no information on which to base a judgement about risk of bias, n = 1 study). CONCLUSION Currently, there is insufficient evidence to support or deny the presence of an association between the probability of pregnancy and serum E2 levels on the day of triggering final oocyte maturation with hCG in women undergoing ovarian stimulation for IVF.