Fetal alpha-melanocyte-stimulating hormone levels: no correlation with late fetal growth but increased with diabetes mellitus.

The pars intermedia of the fetal pituitary produces alpha-melanocyte-stimulating hormone. Previous reports suggest that alpha-melanocyte-stimulating hormone may be a determinant of early fetal growth in animal models. Based on anencephalic fetuses, a similar role was suggested in humans. To examine its relationship to late human fetal growth, alpha-melanocyte-stimulating hormone levels were measured by radioimmunoassay in 185 umbilical cord blood samples from anatomically normal fetuses of 28 to 42 weeks' gestation. With use of stepwise multiple regression analysis, no significant relationship was demonstrated between alpha-melanocyte-stimulating hormone levels and fetal growth. However, significantly higher levels were found in infants of diabetic mothers (p less than 0.05) independent of birth weight, gestational age, or both. No significant relationship with other maternal factors related to fetal growth, labor, and delivery was demonstrated. We conclude that fetal plasma alpha-melanocyte-stimulating hormone levels do not correlate with late human fetal growth. It is speculated that increased alpha-melanocyte-stimulating hormone levels among infants of diabetic mothers might be related to altered neurological maturation.