P-502 Higher progesterone levels on the day of frozen embryo transfer is associated to better reproductive outcomes and higher obstetric complications: a retrospective cohort study
Authors: Paula C , Melo A , Barreto J , Ishimura R , Barboza R , Castro T , Silva M , Sales A , Bueno B 
Published: June 2023

Study question

Can serum progesterone (P) levels on the day of frozen embryo transfer (ET) compromise reproductive outcomes and/or obstetric complications?

Summary answer

Serum P levels was related to higher clinical pregnancy rate on frozen ET cycles. However, women with P level≥8.8 ng/ml presented higher obstetric complications.

What is known already

P levels &lt;9.2 ng/ml on the day of ET significantly decreased ongoing pregnancy rate (OPR) in 211 donated oocyte cycles. In another study of the same group, serum P levels &lt;8.8 ng/ml on the day of ET presented lower OPR in both own or donated oocyte cycles. Another study shown that low serum P4 the day prior to euploid FET can benefit from association of injectable P and achieve similar reproductive outcomes compared to those with initial higher P levels.

Study design, size, duration

This is a retrospective cohort study that included 509 women who have undergone frozen embryo transfer. In this study was included only first cycle of each patient. The women were divided into two groups according P levels: 1) P level &lt;8.8 ng/ml (n = 388) and 2) P level≥8.8 ng/ml (n = 121). The analysis included the period between 01 January 2020 to 31 December 2021.

Participants/materials, setting, methods

All participants of study who underwent frozen ET after an artificial endometrial preparation cycle with estradiol valerate or 17βestradiol and vaginal micronized progesterone(600 mg/day). Age, body mass index(BMI), cause of infertility, and reproductive outcomes(clinical pregnancy, miscarriage, twin pregnancy, live birth rates) and obstetric complications (prematurity, ectopic pregnancy, acretism, hypertensive syndrome in pregnancy, gestational diabetes, intrauterine growth restriction rates) were analyzed. Only women without uterine abnormalities and with endometrium≥6.5 mm were included in this study.

Main results and the role of chance

Clinical pregnancy rate did not significant statistical between the 1 and 2 groups. Live birth rate (p = 0.01) was significantly higher in group 2. Other reproductive outcomes were similar between the groups. In relation to obstetric complications, miscarriage rate was significantly higher in group 1 (p &lt; 0.01) and prematurity (&gt;0.01), acretism (&gt; 0.01), and gestational diabetes (p = 0.01) rates were higher in group 2. The P level did not present relation to cause of infertility. The logistic regression analysis shown that only good embryo quality was predictor to clinical pregnancy rates.

Limitations, reasons for caution

These outcomes were shown only in women without uterus abnormality and that used vaginal progesterone. It is necessary caution to considerer these results to general population. Furthermore, serum P level was analyzed in single moment without definition of interval between last vaginal P dose administration and blood sample collected.

Wider implications of the findings

Monitoring P levels on FET day should be performed routinely on artificial cycles because it can be related to higher live birth rate. However, new studies can confirm if higher P levels on FET day or adjust of P level according P value will be related to better reproductive outcomes.

Trial registration number

not applicable