Amniotic fluid concentrations of immunoreactive prolactin were measured during the third trimester in 184 diabetic gravidas and correlated with concurrent levels of prolactin in maternal plasma. Prolactin measurements concorded with previously published estimates in normal gravid women and averaged 825 ± 32 ng/mL (mean ± SEM) in amniotic fluid and 168 ± 6.5 ng/mL in simultaneously sampled plasma. Cross-sectional and longitudinal analyses indicated that the prolactin levels in amniotic fluid of pregnant diabetics declined significantly between weeks 32 and 40 of gestation, whereas plasma levels did not change consistently during the same interval. Mean values for amniotic fluid prolactin did not correlate with simultaneous prolactin concentrations in plasma, nor with maternal age, clinical estimates of polyhydramnios, amniotic fluid creatinine content, or lecithin/sphingomyelin ( L S) ratios or subsequent birth weight of the offspring. Clear-cut correlations with overall maternal glucose regulation could not be demonstrated. However, subtle effects may be operative since amniotic fluid prolactin displayed weak but significant correlations with concurrent levels of maternal plasma glucose, and mean values for hemoglobin A1c (HbA1c) but not with mean values for fasting plasma glucose (FPG). Amniotic fluid prolactin concentrations were significantly greater in patients with pregestational diabetes (White classes C, D, and F) than in women with gestational diabetes mellitus (GDM) (our classes A1, A2, and B1). The differences could not be accounted for by differences in metabolic regulation, maternal age, or weights of these two populations. We suggest that the higher concentrations of prolactin in the amniotic fluid of White class C, D, and F diabetic gravidas may be related to some aspect of the longer duration or the genotypic features of their diabetes although some contributions via poorer metabolic regulation also may be contributory.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism