O-200 Frozen embryo transfer: Miscarriage rates depending on the starting day of intramuscular progesterone

Study question

Objective was to assess whether adjusting starting day of intramuscular progesterone the day of vaginal supplementation versus day of embryo transfer or later, might affect the outcome of the cycle.

Summary answer

additional injection of intramuscular progesterone the day of progesterone initiation or later, is not likely to be more effective on live birth and miscarriage rates.

What is known already

There is no consensus on the most effective method of endometrium preparation prior to FET. However, many studies report that high serum progesterone concentration during the implantation period is associated with optimal live birth rates. Adjusting progesterone treatment the day of embryo transfer seems to be too late and ineffective for rescuing low progesterone levels and should be done before.

Study design, size, duration

In this single center prospective study from October 2019 to november 2020, 239 patients undergoing hormonal replacement therapy protocol for frozen embryo transfer were randomly divided into two groups: additional injection of intramuscular progesterone the day of progesterone initiation or intramuscular progesterone the day of embryo transfer. We compare these results to our previous protocol beginning intramuscular progesterone day 22 of the treatment.

Participants/materials, setting, methods

Our frozen embryo transfer protocol consists to initiate GnRH agonist the day 1 of the cycle. After 14 days of estrogens, we introduce vaginal progesterone, prior to embryo transfer. Patients in group A received an additional injection of intramuscular progesterone the day of progesterone initiation. The group B received intramuscular progesterone the day of embryo transfer. For both, intramuscular injection of progesterone was followed every 3 days.

Main results and the role of chance

239 patients were enrolled in this study, 125 in the group A and 114 in the group B. The ongoing pregnancy rate in the group A was 26.4 % and miscarriage rate 7.2%, not statistically different from ongoing pregnancy rate and miscarriage rate of women in the group B (22.81 %, p = 0.66/ 6.14%, p = 0.8).

The ongoing pregnancy rate in the group D22 was 24.89 % et miscarriage rate 7.2%, not statistically different from ongoing pregnancy rate of women in the group A and B (p = 0.78 and p = 0.31).

Limitations, reasons for caution

The main limitation of our study is the lack of randomization for the group with additional progesterone IM on day 22. The study is actually followed to enroll more patients in 3 different groups.

Wider implications of the findings

This study tries to determine optimal adaptive management of hormonal replacement treatment for embryo transfer in patients with potential low progesterone values.

Trial registration number

no applicable