Mau Kai C et al. (2007) Reduced serum testosterone levels in infant boys conceived by Intracytoplasmic sperm injection (ICSI). J Clin Endocrinol Metab 92: 2598–2603

Boys conceived using intra-cytoplasmic sperm injection (ICSI) have lower serum testosterone levels than their naturally conceived counterparts, according to a recent study from Denmark where 1.5% of all children are conceived using ICSI.

ICSI is an increasingly popular technology for overcoming male infertility. Previous evidence has suggested that impaired testicular function might be passed on from father to son when this technique is used, but the possibility of impaired Leydig cell function in ICSI offspring has not previously been investigated.

Mau Kai and colleagues compared serum levels of luteinizing hormone, follicle stimulating hormone, sex-hormone-binding globulin, inhibin B, and testosterone in boys conceived using ICSI (n = 125), boys conceived using in vitro fertilization (n = 124), and boys conceived naturally (n = 933) in a prospective, longitudinal cohort study. Measurements were taken at birth and, in most cases, at 3 months of age.

The results showed that boys conceived using ICSI had significantly lower serum testosterone levels compared with boys conceived naturally (P <0.001), and a higher luteinizing hormone to testosterone ratio (P = 0.001). By contrast, both serum testosterone levels and luteinizing hormone to testosterone ratio were normal in the boys conceived using in vitro fertilization because of female infertility factors.

These results suggest that boys conceived using ICSI might have a subtle impairment of Leydig cell function that could have been inherited from their fathers. The authors conclude that, given the increasing popularity of ICSI, these findings should raise concern, although their clinical relevance remains unclear.