Vaginal Progesterone Gel for Luteal Support After Cleavage Stage Embryo Transfer Once or Twice a Day?

OBJECTIVE: To determine whether twice daily dosing of progesterone vaginal gel (PVG) is better for luteal phase support (LPS) than once daily dosing. STUDY DESIGN: Retrospective study including 456 women aged <= 42 years who underwent assisted reproductive technology with long GnRH agonist protocol. Blastocyst transfers and difficult embryo transfers were excluded. LPS was started with 90 mg PVG once daily on the evening of oocyte retrieval and continued until negative pregnancy test or 10th week of pregnancy in both groups. PVG dosage was doubled on the day of embryo transfer in the twice-daily group. RESULTS: Age, duration of infertility, and number of oocytes collected were similar. Numbers of embryos transferred were 2.9 and 2.8 in the once-daily and twice-daily groups, respectively (p=0.04). Embryo implantation (23.96% vs. 27.95%) and clinical pregnancy (50.9% vs. 56.5%) rates favored twice-daily dosage; however, differences were statistically nonsignificant, and the study had 20% power to demonstrate significance. When our results were pooled with a prior trial comparing once and twice daily dosing, twice daily dosing seemed to significantly increase clinical pregnancy rate (rate ratio: 1.18, 95% CI 1.01-1.38). CONCLUSION: Trends favoring twice daily dosing are encouraging findings and require further investigation.