CIRCULATING LEVELS OF GROWTH-HORMONE, INSULIN-LIKE GROWTH-FACTOR-I AND PROLACTIN IN NORMAL, GROWTH-RETARDED AND ANENCEPHALIC HUMAN FETUSES

We measured growth hormone (GH), insulin-like growth factor-I (IGF-I), and both total and glycosylated prolactin (PRL) levels in 131 blood s amples obtained by cordocentesis in normal and abnormal fetuses from 1 9 to 40 weeks of gestation. in normal fetuses, IGF-I and PRL levels sh owed a positive correlation and GH a negative correlation with gestati onal age. A negative relation between GH and IGF-I levels was observed , while PRL did not show any correlation with both GH and IGF-I concen trations. lGF-I increased from 5.6+/-3 fat 19-22 weeks) to 10.7+/-5 nm ol/l at term; GH decreased from 31+/-10 to 7.7+/-4 mu g/l and PRL incr eased from 16+/-18 to 139+/-76 mu g/l. Glycosylated PRL accounted for about 15% of total PRL, a value similar to that found in normal adults . in 27 fetuses of 27-37 weeks with intra-uterine growth retardation, GH and PRL levels were higher and IGF-I levels lower than in normal fe tuses matched for week of gestation. In 8 anencephalic fetuses of 19-2 6 weeks of gestation, both GH and IGF-I levels were lower, and PRL lev els were higher than in matched controls. Altogether these data suppor t the views that a) both GH and PRL secretion are under the hypothalam ic control during fetal development, b) the serum GH deGrease from mid gestation to the end of pregnancy is mediated by the negative feed-bac k mechanism of increasing IGF-I levels and c) IGF-I production is main ly regulated by fuel supply and only partially by GH.