The effect of oestrogen dose and duration in programmed frozen cycles on obstetric outcomes and placental findings

Does programmed frozen embryo transfer (FET) with high-dose oestrogen affect obstetric outcomes and placental findings? A retrospective cohort of live singleton deliveries at a single institution between 2009 and 2017, including deliveries attained by IVF with programmed FET; oocyte recipients were excluded. High-dose oestrogen was defined as a daily dose >6 mg throughout treatment. All placentas were evaluated regardless of complication status and the Amsterdam classification was used to analyse findings. A total of 57 deliveries in the high-dose oestrogen group were compared with 274 controls. The high-dose oestrogen group displayed significantly longer duration of oestrogen treatment (18.8 ± 4.9 versus 13.3 ± 2.7 days, P