OBJECTIVE:

To summarize the available published randomized controlled trial data regarding timing of P supplementation during the luteal phase of patients undergoing assisted reproductive technology (ART).

DESIGN:

A systematic review.

INTERVENTION(S):

Different starting times of P for luteal support.

MAIN OUTCOME MEASURE(S):

Clinical pregnancy (PR) and live birth rates.

RESULT(S):

Five randomized controlled trials were identified that met inclusion criteria with a total of 872 patients. A planned meta-analysis was not performed because of a high degree of clinical heterogeneity with regard to the timing, dose, and route of P. Two studies compared P initiated before oocyte retrieval versus the day of oocyte retrieval and PRs were 5%-12% higher when starting P on the day of oocyte retrieval. One study compared starting P on day 6 after retrieval versus day 3, reporting a 16% decrease in pregnancy in the day 6 group. Trials comparing P start times on the day of oocyte retrieval versus 2 or 3 days after retrieval showed no significant differences in pregnancy.

CONCLUSION(S):

There appears to be a window for P start time between the evening of oocyte retrieval and day 3 after oocyte retrieval. Although some studies have suggested a potential benefit in delaying vaginal P start time to 2 days after oocyte retrieval, this review could not find randomized controlled trials to adequately assess this. Further randomized clinical trials are needed to better define P start time for luteal support after ART.