Perinatal outcomes of progesterone in natural frozen-thawed embryo transfer pregnancies: insights from 2 randomized controlled trials

Our study demonstrates the absence of harmful perinatal effects associated with the use of vaginal progesterone supplementation at the luteal phase and early pregnancy of an NC-FET cycle. These findings have increased generalizability across other populations and are particularly significant given the growing utilization of cryopreservation and freeze-all practice in assisted reproduction. The associations noted between progesterone supplementation and certain perinatal outcomes warrant further investigation.