Intramuscular versus vaginal progesterone in assisted reproduction: a comparative study

The effectiveness and the absorption of two progesterone (P) presentations have been compared for luteal phase support of patients aged < or = 37 years undergoing an in vitro fertilization (IVF) procedure for the first time, who were stimulated after pituitary desensitization with gonadotrophin releasing hormone agonists (GnRHa). All of them had two ovaries, normal ovarian functions and normal endometrial morphology: the indication for the assisted reproductive technique was the tubal factor. Two hundred and fifty patients were randomly allocated to two groups in order to compare two treatment protocols: Group A: natural i.m. P (50 mg/day, Prontogest, AMSA, Italy); Group B: micronized vaginal P (200 mg/day Esolut, Angelini, Italy). We were able to show that the i.m. P resulted in a higher percentage of pregnancies than the vaginal preparation, with statistically significant differences. We recommend the use of injectable P, and suggest reserving intravaginal P as a second choice for patients who cannot tolerate intramuscular administration.