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

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