Increased obstetric and neonatal risks in artificial cycles for frozen embryo transfers

Abstract Research question what are the obstetric and neonatal risks of women who conceived through frozen-thawed embryo transfer (FET) during a modified natural cycle (NC) compared to an artificial cycle (AC) method. Design we performed a follow up study of the ANTARCTICA RCT (NTR 1586) which was conducted in the Netherlands. This RCT showed that modified NC-FET was non-inferior to AC-FET in terms of live birth rates. We now collected data on obstetric and neonatal outcomes of ninety-eight women who had a singleton live birth. The main outcome of the current study was birth weight, additional outcomes included hypertensive disorder of pregnancy, premature birth, gestational diabetes, obstetric hemorrhage and neonatal outcomes including Apgar scores and admission to the neonatal ward or the neonatal intensive care unit and congenital anomalies. Results Data from 82 out of 98 women were analysed according to the per protocol principle. There was no significant difference between the birth weights of children born between groups (mean difference -124 grams (-363 grams to 114 grams); p=0.30)). Women who conceived by modified NCFET have a decreased risk of hypertensive disorders of pregnancy compared to ACFET (RR 0.27 (CI 95% 0.08-0.94); p=0.031). Other outcomes, such as rates of premature birth, gestational diabetes or obstetric hemorrhage and neonatal outcomes, were not significantly different. Conclusions Our interpretation is that modified NC-FET is the preferred treatment in women with ovulatory cycles undergoing FET when we consider the increased risk of obstetrical complications and potential neonatal complications in AC-FET. Study funding None