OBJECTIVE: To perform an analysis of data with consideration for the current clinically accepted vaginal progesterone (P) or intramuscular (IM) P dosing regimens and the clinically relevant randomized clinical trials published during the time frame 1992 to 2008. DESIGN: Meta-analysis of progesterone luteal support in IVF cycles using odds ratios (OR) and 95% confidence intervals (CI). SETTING: Previously conducted randomized clinical trials meeting acceptance criteria. PATIENT(S): Infertility patients. INTERVENTION(S): Progesterone (50 mg) IM daily or 200 mg P-in-oil capsules three times a day vaginally or 90 mg P in bioadhesive gel daily vaginally. MAIN OUTCOME MEASURE(S): Clinical pregnancy, ongoing pregnancy, miscarriage. RESULT(S): This analysis showed a comparable effect between vaginal progesterone as an oil-in-capsule or as a bioadhesive gel and IM P administration on the endpoints of clinical pregnancy (OR = 0.91, 95% [CI 0.74, 1.13]) and ongoing pregnancy (OR = 0.94, 95% [CI 0.71, 1.26]). A nominally significantly lower rate of miscarriage was observed with vaginal P compared with IM P (OR = 0.54, 95% [CI 0.29, 1.02]). CONCLUSION(S): Administration of vaginal P is comparable to administration of IM P for luteal phase support in assisted reproductive technology.