Pereira N, et al. - A retrospective cohort study is carried out to explore the utility of cycle day (CD) 28 hCG, estradiol (E₂) and progesterone (P) levels in predicting live birth in patients undergoing frozen embryo transfer (FET) cycles. Based on these outcomes, combination of CD 28 hCG, E2 and P are superior to individual CD 28 hormone levels in predicting live singleton births in patients undergoing FET cycles. The combined predictive utility of these hormones is better in natural FET cycles than programmed FET cycles.