The relationship between weight gain during pregnancy and allopregnanolone levels: a longitudinal study.

OBJECTIVE: Large weight gain during pregnancy is a risk factor for complications for mother and fetus. Hunger and satiety are regulated in the hypothalamus, where the gamma-amino-butyric acid system (GABA) has an important role. Allopregnanolone, a progesterone metabolite, increases during pregnancy and is a potent GABA-A receptor modulating steroid. Allopregnanolone has been shown to induce overeating in rodents. The aim was to investigate whether there is a relationship between weight gain and allopregnanolone concentrations during pregnancy in humans.

DESIGN: A longitudinal, cohort study.

METHODS: Pregnant women ( n  = 56) were recruited in primary care in northern Sweden. Allopregnanolone concentrations in plasma were measured using radioimmunoassay and weight was measured in gestational weeks 12 and 35.

RESULTS: Weight increase correlated significantly to allopregnanolone in late pregnancy increase ( r s  = 0.320; P  = 0.016), indicating a positive relationship between weight increase and allopregnanolone increase. A positive relationship was also noted between allopregnanolone in the 35th gestational week and weight increase. Women who gained ≥11 kg during pregnancy showed higher allopregnanolone concentrations in week 35 and higher increase compared to women who increased <11 kg ( P  = 0.006 and P  = 0.009 resp.). There was no difference in weight or allopregnanolone concentrations at the onset of pregnancy.

CONCLUSIONS: The results show a relationship between weight gain during pregnancy and increase in allopregnanolone concentrations.