[A study of two different routes of administration of micronized progesterone in assisted reproduction].

Background: Progesterone is almost completely absorbed after administration by oral route when its preparation is micronized, but, due to the important metabolic inactivation during the first hepatic pass, bioavailability of oral progesterone is notably poor reaching values lesser than 10%.

Objective: To compare two different routes of administration of progesterone for luteal phase support in artificial insemination protocols.

Material And Methods: 24 patients were randomly allocated in the 2 arms of the study, 200 mg/daily, vaginally or p.o. Plasma levels of progesterone were analyzed and ultrasound was performed to compare endometrium pattern and thickness.

Results: No differences were found in terms of indication, semen parameters, number of preovulatory follicles and progesterone serum levels. Endometrial pattern and thickness were clinical and statistically better in group I as the pregnancy rate.

Discussion: Taking in account our results we can argue that vaginal progesterone improve endometrial features favoring implantation and pregnancy rates without modifying progesterone serum levels.