MATURATION OF GONADOTROPHIC FUNCTION IN THE PREMATURE NEONATE

Abstract

In order to study gonadotropin secretion in the second half of pregnancy LH and FSH plasma levels were estimated in cord sera from 28 premature and 19 mature neonates as well as serially at weekly intervals in 45 prematures postnatally (p.n.)(22 ♂,23 ♀; gestational age (g.a.) 26-34 wks). Results: LH and FSH cord levels were higher in the premature group for both girls (P<0.05) and boys (P<0.01) compared to mature neonates. There was no sex difference. Prematures were divided in 3 groups according to g.a.: a:26-28 wks, b:29-30 wks, c:31-33 wks. P.n. from week 2 onwards a strong FSH increase was present only in the premature girls with a trend towards longer FSH elevation in the infants with a shorter g.a. FSH was higher when g.a. was shorter (P<0.05).In premature boys FSH was low and showed no p.n. rise. LH levels declined the first week p.n. in girls and boys. In girls a transient increase was seen from week 2 onwards. This increase was stronger and longer in duration when g.a. was shorter. From wk 7-10 LH was higher in gr.a than in gr.c (P<0.01). Conclusions: gonadotropin cord levels decrease with progression of gestational age without sex difference. Postnatally the sex difference (low gonadotropin levels in boys and high levels in girls) may be explained either by a more developed central inhibition of gonadotropin secretion, the so-called ‘intrinsic restraint’, or by a stronger activity of negative feedback by gonadal products in boys than in girls