Decreased fetal cord prolactin concentration in diabetic pregnancies.

Infants of diabetic mothers are known to have a greater incidence of respiratory distress syndrome than normal control infants. Fetal lung maturation is modulated by a large number of hormones. To further investigate a possible role of hormonal modulators of lung maturation in infants of diabetic mothers, fetal cord prolactin, estrone, estradiol, thyroxine, triiodothyronine, and triiodothyronine-resin uptake index levels were measured in infants of diabetic mothers (n = 40) and nondiabetic mothers (n = 40) at term. Infants of diabetic mothers had significantly lower mixed-cord serum prolactin levels (p less than 0.0005) than control infants. There was no significant difference in cord serum thyroxine, triiodothyronine-resin uptake index, triiodothyronine, estrone, or estradiol levels between the infants of diabetic mothers and the infants of control mothers. These findings raise the possibility that decreased fetal prolactin levels may be associated with, or contribute to, the delayed lung maturation reported with diabetic pregnancies.