Inhibin A, inhibin B, follicle-stimulating hormone, luteinizing hormone, estradiol, and sex hormone-binding globulin levels in 473 healthy infant girls

The early postnatal regulation of reproductive hormones seems to be more complex in girls than in boys. The aim of this study was to describe inhibins A and B, FSH, LH, estradiol, and SHBG in a large prospective cohort of 473 unselected, healthy, 3-month-old girls. In full term, appropriate-for- gestational-age girls (n = 355) hormones showed a marked interindividual variation, with concentrations up to pubertal values [medians (95% confidence intervals): inhibin B, 82 pg/ml (<20–175); FSH, 3.8 IU/liter (1.2–18.8); LH, 0.07 IU/liter (<0.05–1.07); estradiol, 31 pm (<18–83); SHBG, 137 nm (72–260)]. In 38%, FSH levels exceeded 4.5 IU/liter. Weight at 3 months had significant inverse relationships with estradiol and SHBG (P = 0.048 and P = 0.001, respectively). Gestational age was negatively correlated to estradiol (P = 0.001), with a similar trend for LH, FSH, and inhibin B. Inhibin B was higher in premature girls [126 pg/ml (<20–265)] than in term [80 pg/ml (<20–181), P = 0.002] and postmature girls [59 pg/...