Ratio of progesterone-to-number of follicles as a prognostic tool for in vitro fertilization cycles.

Purpose: To establish a ratio of the P level to the number of follicles (P/F ratio) on the day of human chorionic gonadotropin (hCG) administration and to evaluate whether this ratio is associated with in vitro fertilization (IVF) outcome.

Methods: This study was conducted between January 2012 and June 2013. A total of 337 patients with cleavage-stage day-3 fresh embryo transfer with P levels ≤1.5 ng/mL on the day of hCG administration were included in the study. The main outcome was ongoing pregnancy rate.

Result(s): The P/F ratio was calculated according to the equation (P[ng/mL]/number of follicles) on the day of final oocyte maturation. Using ROC, we established a cut-off level of 0.075 for the P/F ratio. The area under the curve (AUC) (0.756; 95 % confidence interval [CI]: 0.704-0.807) indicated that it was a good prognostic test. In group 1 (patients under 36 years old), the ongoing pregnancy rates were 57 and 30 % for patients with P/F ratios ≤ .075 and > .075, respectively, (p = 0.003). In group 2 (patients between 36 and 39 years old), the ongoing pregnancy rates were 58 % and 17 % (p = 0.001) for patients with P/F ratios ≤ .075 and > .075, respectively. In group 3 (patients ≥ 40 years old), the ongoing pregnancy rates were 41.7 and 10.9 % (p = 0.001) for patients with P/F ratios ≤ .075 and > .075, respectively.

Conclusions: The P/F ratio is a good prognostic test for predicting IVF outcome that can correlate the P level with ovarian response.