Fetal antecedents of male factor sub-fertility: how important is birthweight?

BACKGROUND: Severely reduced fetal growth has been linked to gonadal dysfunction. The aim of this study was to explore the link between birthweight and subsequent male infertility using the Aberdeen Maternity and Neonatal Databank (AMND). METHODS AND RESULTS: Assuming 80% power at the 5% significance level, a minimum of 126 men (63 in each group) was required to show a mean difference of 0.5 (SD = 1) in the standardized birthweight scores between cases and controls. Men born locally with unexplained male factor infertility (n = 79) were identified from the infertility clinic database. Men with normal semen parameters, born in Aberdeen and attending the infertility clinic with their partners (n = 104), served as controls. The pregnancy records of these men's mothers were obtained from the AMND and a standard case-control analysis performed. In addition to standardized birthweight scores, the following variables were studied: crude birthweight, social class, maternal age, parity, obstetric history, antepartum and peripartum events. CONCLUSIONS: No differences were found between the two groups, suggesting that low birthweight is unlikely to affect male fertility in later life.