Objective: We aimed to determine whether metformin when taken during a fresh in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycle affects live birth rate (LBR) in subsequent frozen embryo replacement cycles (FERC).
Design: A retrospective database analysis of women with polycystic ovary syndrome (PCOS) undergoing FERC at a university teaching hospital between 2002 and 2007 (n = 142). The outcome of FERC in women who had taken metformin in the 'fresh' IVF/ICSI cycle (group A, n = 28) and those who had not (group B, n = 114) were compared.
Results: In the first FERC there was a significantly higher LBR (A = 28.6%, B = 12.3%, OR 2.86 95% CI 1.06-7.71). Women who had elective cryopreservation due to ovarian hyperstimulation syndrome risk were found to have significantly higher LBRs if metformin was taken in the fresh IVF/ICSI cycle (A = 44.4%, B = 7.9%, OR 9.33 95% CI 1.60-54.58).
Conclusions: Women with PCOS who take metformin during IVF/ICSI may have a higher LBR in subsequent FERC, especially in those who have elective cryopreservation for OHSS risk. The findings of this study are limited by its retrospective design and small sample size and require confirmation in an adequately powered prospective randomized controlled trial.