Luteal phase support for natural cycle frozen embryo transfer: a meta-analysis

Purpose We aimed to evaluate the effect of luteal phase support (LPS) on pregnancy outcome in natural cycle frozen embryo transfer (NC-FET).Method We searched PubMed, Cochrane Library, Embase for related literature from start to February 2020. Relative risk ratio (RR) and 95% confidence intervals (95% CI) in random-effects, fixed-effects models were calculated using Review Manager 5.3.Results Totally 9 studies were included in the meta-analysis. The results showed no significant difference could be found regarding chemical pregnancy rate (RR 1.07, 95% CI 0.93–1.22; I2 = 54%) and miscarriage rate (RR 0.92, 95% CI 0.70–1.22; I2 = 0%) between the LPS groups and no LPS groups in NC-FET. LPS groups has increased the rate of clinical pregnancy rate (RR 1.23, 95% CI 1.12–1.34; I2 = 52%) compared with no LPS groups. Subgroup analysis according to trigger administration also showed a significant difference between the two groups.Conclusion LPS might improve the clinical pregnancy rate in NC-FET. HCG trigger for ovulating may result in luteal phase deficiency. LPS subsequently improved clinical pregnancy rate and chemical pregnancy rate for patients undergoing HCG trigger and NC-FET.Retrospectively registered This meta-analysis was registered at PROSPERO, PROSPERO ID is CRD42020171758.