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Endometrial receptivity and pregnancy rates are higher after 7 days of progesterone in medicated FET cycles


To determine if Endometrial Receptivity Analysis (ERA) testing will improve implantation and pregnancy rates in patients undergoing medicated frozen embryo transfer (FET) cycles.


Retrospective study in a large private practice fertility clinic.


We included all patients who had one or more ERA tests (Igenomix) in our clinic from 1/2016 to 5/2017. Patients were treated with oral and/or vaginal estradiol and begun on vaginal or intramuscular progesterone when the endometrial thickness was 7 mm or more and the serum progesterone level was less than 1 ng/ml. The first endometrial biopsy ERA test was done on the sixth day of progesterone. Patients who had a receptive ERA on day 6 of progesterone had a medicated FET with the transfer on day 6 of progesterone. Patients who had a pre-receptive ERA on the sixth day of progesterone were offered a repeat ERA or FET on day 7 of progesterone. A serum quantitative hCG was drawn 9 days after a blastocyst FET and repeated 48 to 72 hours later. A transvaginal ultrasound was performed by 7.5 weeks estimated gestational age. Statistical calculations were performed with a Chi-Squared test.


A total of 85 women, ages 27-51, had an ERA test on the 6th day of progesterone. The majority of patients had a prior failed FET (70%). Only 24% of the ERA tests on day 6 of progesterone were receptive (Table 1). Repeat ERA testing on day 7 of progesterone was performed on 38 patients. The majority of day 7 progesterone patients had an ERA test that was receptive (79%). Ninety percent of patients had a single embryo transfer and 10% a double embryo transfer. The pregnancy rates were significantly higher in our patients having an embryo transfer on the seventh day of progesterone.


Women undergoing a medicated FET cycle were significantly more likely to have a receptive endometrium, by ERA testing, on the 7th day of progesterone. There were also higher pregnancy rates in women having a transfer on the 7th day of progesterone in medicated FET cycles.

Day 6 or Day 7 of Progesterone

Days of Progesterone Pre-Receptive ERA Receptive ERA Post-Receptive ERA PGS Embryos Pregnacy Rate per FET Ongoing Rate Per FET
Day 6 74.1% 23.5% 2.4% 61.1% 55.6% 44.4%
Day 7 7.8% 78.9% 13.2% 68.4% 81.6% 71.1%
p value p<0.01 p<0.01 p=0.58 p=0.59 p=0.04 p=0.05

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