Impact of administration route on serum progesterone levels in women undergoing artificial endometrial preparation

Objective

Are there differences in serum progesterone levels between different routes of exogenous progesterone administration for artificial endometrial preparation?

Material and methods

This prospective, observational, single-centre study included 9 infertile female patients who underwent cycles of artificial endometrial preparation between January and June 2019 with different progesterone formulations (3 cycles in 2 patients; 2 cycles in 2 patients; and 1 cycle in 5 patients). Oestrogen stimulation was followed by vaginal progesterone 400 mg every 12 h (first cycle), subcutaneous progesterone 25 mg every 12 h (second cycle), and intramuscular progesterone 50 mg every 24 h (third cycle). Progesterone therapy was continued for 5 days and daily serum progesterone was recorded. The primary outcome was day 5 serum progesterone.

Results

Day 5 mean ± standard deviation serum progesterone levels after vaginal, subcutaneous, and intramuscular administration were 14.6 ± 5.5, 47.9 ± 22.3, and 60.3 ± 65.5 ng/mL, respectively (p = 0.032 across routes). From day 1 to day 5, the coefficients of variation for serum progesterone were 66% and 75% with the vaginal and subcutaneous routes, respectively, indicating low variability, and 146% with the intramuscular route, indicating high variability. Two linear regression models were conducted: a normal linear regression model, which found no significant effect of administration route on serum progesterone, and a mixed-effects linear regression model, which also showed no statistically significant differences between routes.

Conclusion

All routes of progesterone administration showed satisfactory day 5 mean serum progesterone levels, regardless of administration route.