The association between endogenous LH concentrations during ovarian stimulation in a gonadotrophin-releasing hormone (GnRH) antagonist protocol and pregnancy likelihood was examined in a large combined analysis of individualized patient data obtained after treatment with recombinant FSH and a GnRH antagonist prior to IVF/intracytoplasmic sperm injection. Data from 1764 patients from six randomized controlled trials were pooled for retrospective analysis. Ongoing pregnancy and miscarriage rates for patients stratified by LH percentiles were assessed. Patients in the lowest LH quartile (< P25) were younger with a higher predicted ovarian reserve and response compared with patients in the highest quartile (> P75). With adjustment for identified predictive factors of pregnancy, estimated odds ratios (95% confidence interval) for ongoing pregnancy for LH categories < P25 versus ≥ P25, > P75 versus ≤ P75 and < P25 versus > P75 were 0.96 (0.75-1.22), 1.13 (0.88-1.45) and 0.89 (0.66-1.21) on stimulation day 8, and 0.96 (0.76-1.21), 1.03 (0.82-1.30) and 0.95 (0.72-1.26) on the day of human chorionic gonadotrophin, respectively. No significant differences in pregnancy or miscarriage rates between the LH categories were observed. Endogenous LH concentrations have no association with the likelihood of ongoing pregnancy in women undergoing ovarian stimulation using a recombinant FSH/GnRH antagonist protocol.