Gonadal Function in Low Birth Weight Infants: A Pilot Study

OBJECTIVE: To evaluate gonadal function and anti-Müllerian hormone (AMH) serum concentrations during the first 3 months of life in low birth weight (low-BW) and normal birth weight (normal-BW) infants. INFANTS: Twenty low-BW and 29 normal-BW infants were studied. METHODS: The pituitary-gonadal axis was evaluated by a GnRH agonist test (leuprolide acetate, 10 microg/kg s.c.). Circulating concentrations of gonadotropins, steroid hormones, sex hormone binding globulin, inhibin B and AMH were determined by specific assays. RESULTS: In both sexes, basal concentrations of gonadotropins, sex steroids, sex hormone binding globulin and inhibin B were similar between low-BW and normal-BW infants. However, AMH concentrations were significantly higher in low-BW compared to normal-BW females (p = 0.004). This was not observed in males. After leuprolide administration, estradiol concentrations were higher in low-BW compared to normal-BW females (p = 0.043). In males, post-stimulated sex steroid concentrations were similar in both groups except for 17-OHP, which was significantly higher after leuprolide in the low-BW group (p = 0.023). CONCLUSIONS: An increase in AMH and post-stimulated estradiol serum concentrations suggests altered follicular development in low-BW girls. In contrast, the normal circulating levels of AMH and inhibin B seem to indicate that Sertoli cell function is normal in low-BW boys. We suggest that ovarian function seems to be more vulnerable than testicular function in infants with intrauterine growth restriction.