Vaginal micronized progesterone versus intramuscular progesterone for luteal support in women undergoing in vitro fertilization-embryo transfer

Objective: To study the outcome of IVF-ET in women who used vaginal P (vaginal P₄) versus those who used P in oil via IM injection (IM-P₄) for luteal support. Design: Retrospective cohort. Setting: Tertiary referral infertility center. Patient(s): A cohort of 544 women. Intervention(s): In 145 women, vaginal P₄ was used, while in 399 women, IM-P₄ was used for luteal support. Main Outcome Measure(s): The primary outcome was ongoing pregnancy rate. Secondary outcomes included other IVF-ET outcomes: rates of clinical pregnancy and pregnancy loss (chemical and miscarriage) and serum P levels during the luteal phase and early pregnancy. Result(s): Women who used vaginal P₄ for luteal support had ongoing pregnancy rates (odds ratio [OR], 1.0675; 95% confidence interval [CI], 0.7587-1.5020) and rates of total pregnancy loss (OR, 1.0775; 95% CI, 0.7383-1.5727) that were not statistically different from those who used IM-P₄. During the luteal phase, women who used vaginal P₄ had mean serum P levels that were not statistically different from those who used IM-P₄. However, during early pregnancy, mean P levels in pregnant women who used vaginal P₄ were statistically significantly higher. Conclusion(s): In women undergoing IVF-ET according to the GnRH agonist long protocol, luteal support with vaginal P₄ was associated with treatment outcomes that were no different from those associated with IM-P₄ luteal support.