Being on the side of old findings: progesterone elevation on the day of oocyte maturation induction does not affect embryological parameters throughout the blastocyst culture period.

Purpose: To investigate whether there is any detrimental effect of progesterone elevation (PE) on the day of oocyte maturation induction on embryological development potentials.

Methods: This retrospective single-center cohort study included a total of 1485 individual intracytoplasmic sperm injection (ICSI) cycles between January 2014 and December 2018. Serum progesterone (P) levels were measured on the day of oocyte maturation induction following the GnRH antagonist suppression protocol. Embryological parameters such as maturation, fertilization rate (FR), top-quality embryo (TQE) formation rate per 2PN on day 3, and excellent-quality blastocyst (EQB) formation rate per 2PN on day 5/6 were recorded. The inclusion criteria for women were an age ≤ 37 years, a BMI ≤ 30 kg/m, and access to a total sperm concentration ≥ 2 million. Groups were stratified according to the serum P levels using the cut-off levels of < 0.8 ng/ml; 0.8-1.49 ng/ml; and ≥ 1.5 ng/ml.

Results: Peak E2 level and total number of oocytes retrieved were significantly related to PE (p < 0.001). FR did not display a significance difference between groups (p = 0.108). The TQE and the blastulation rates were not affected by PE (p = 0.82 and p = 0.68, respectively). Chi square analysis revealed a significant relationship between PE and the EQB formation rate (p = 0.01). GEE analysis failed to present any statistical significance regarding the effect of PE on neither the TQE nor the EQB formation rates per 2PN [OR 1.07; 95% (0.98-1.16) p = 0.113 and OR 0.93; 95% (0.80-1.07) p = 0.32, respectively].

Conclusions: In accordance with previously published papers, our study could not find any detrimental effect of PE on embryological outcomes throughout the blastocyst culture period.