A modified natural cycle frozen embryo transfer (mNC-FET) using exogenous human chorionic gonadotropin (hCG) trigger is a widely used endometrial preparation protocol.The need for luteal phase support (LPS) in mNC-FET remains uncertain.The primary outcome of this systematic review and metaanalysis was the impact of progesterone LPS on live birth rates.Secondary outcomes included clinical pregnancy and pregnancy loss rates.A systematic literature search identified eight eligible studies, of which seven (three randomised controlled trials (RCT) and four retrospective cohort studies) were included in the meta-analysis, comprising 3,896 cycles.Five studies, including the three RCTs, found no benefit of progesterone LPS in mNC-FET.Using study-reported odds ratios (OR) and adjusted odds ratios (aOR), the meta-analysis showed no difference in live birth rate between progesterone LPS and no LPS (OR 1.15, 95% CI 0.98-1.36;aOR 1.07, 95% CI 0.64-1.79).Clinical pregnancy rate increased with LPS in the crude analysis (OR 1.21, 95% CI 1.04-1.40),but not in the adjusted analysis (aOR 1.15, 95% CI 0.87-1.51).Pregnancy loss rate was similar between LPS and no LPS (OR 0.98, 95% CI 0.70-1.38).These results do not support a general benefit of progesterone LPS in mNC-FET.Whether certain subgroups require an individualised approach remains to be determined.
Engesgaard et al. (Wed,) studied this question.