Prospective analysis of progesterone exposure in programmed single thawed euploid embryo transfer cycles and outcomes.

Purpose: In the era of personalized medicine and the increased use of frozen embryo transfer (FET), assay of the endometrium's receptivity prior to transfer has gained popularity, especially among patients. However, the optimal timing for single thawed euploid embryo transfers (STEET) in a programmed FET has yet to be determined Mackens et al. (Hum Reprod. 32(11):2234-42, 2017). We sought to examine the outcomes of euploid FETs by length of progesterone (P4) exposure.

Methods: Prospective cohort study of programmed FETs of single euploid embryos between June 1, 2018, and December, 18, 2018, at our center. Subjects reported the exact start time for initiating progesterone. The transfer time was noted to calculate the primary independent variable, duration of progesterone exposure. Statistical analysis included ANOVA and Spearman's rho correlation, with p < 0.05 considered significant.

Results: Inclusion criteria were met for 253 programmed STEET cycles in the analysis. There was no significant difference in P4 duration when comparing outcome groups (112.8 ± 3.1 ongoing pregnancy (OP), 112.4 ± 4.4 spontaneous abortion (SAB), 111.6 ± 1.7 biochemical pregnancy (BP), 113.9 ± 5.7 no pregnancy (NP), F 1.76, df 3, p = 0.16). An ROC curve assessing the ability of P4 duration to predict ongoing pregnancy (OP) had an area under the curve of 0.467 (p = 0.38).

Conclusion: Duration of P4 was not associated with outcome. Of the cycles, 65.6% resulted in ongoing pregnancy with our center's instructions resulting in an average progesterone exposure of 112.8 h, with a range of 98.3-123.7 h. With growing popularity for individualized testing, these results provide evidence for patient counseling of the high likelihood of ongoing pregnancy without personalized testing.