Study design and participants
allergic reactions
ALLERGIC REACTION
This prospective study was conducted at the Reproductive Medical Center of the Affiliated Hospital of Southwest Medical University. This study included patients who underwent FET in an artificial cycle from April 2021 to October 2021 and were allocated to one of four groups as soon as the endometrial thickness reached 7 mm after estrogen supplementation. One or two embryo(s) were transferred according to Health Commission legislation. The inclusion criteria were patients aged 22−45 years and on hormone replacement cycles. The exclusion criteria included known allergic reactions to progesterone products, uptake of an experimental medicine within 30 days before study initiation, and cancellation of FET for various reasons. The cycles were stratified into four groups based on the duration of progesterone supplementation before embryo transfer and the embryonic development stage. The cycles were assigned to groups P3 or group P5 from April 2021 to June 2021. The cycles were assigned to Groups P4 and P6 from July 2021 to October 2021. Patients in groups P3 and P4 were administered intramuscular progesterone for 3 and 4 days, respectively, before frozen-thawed Day 3 cleavage-stage embryo transfer. Patients in groups P5 and P6 were separately supplemented with intramuscular progesterone for 5 and 6 days, respectively, before the frozen-thawed blastocyst transfer. This trial was performed using one or two vitrified-warmed embryo(s) when the endometrial thickness reached 7 mm after estrogen supplementation in an artificial cycle. This study was approved by the Institutional Review Board of the hospital. Written informed consent was obtained from all participants.