Gains in body mass and body water in pregnancy and relationships to birth weight of offspring in rural and urban Pune, India

Maternal size, weight gain in pregnancy, fetal gender, environment and gestational age are known determinants of birth weight. It is not clear which component of maternal weight or gained weight during pregnancy influences birth weight. We evaluated the association of maternal total body water measured by the deuterium dilution technique (TBW-D2O) at 17 and 34 weeks of gestation with birth weight. A secondary aim was to examine the utility of bioimpedance spectroscopy (BIS) to determine total body water (TBW-BIS) in pregnancy. At 17 and 34 weeks of pregnancy, ninety-nine women (fifty-one rural and forty-eight urban) from Pune, India had measurements of body weight, TBW-D2O, TBW-BIS and offspring birth weight. At 17 weeks of gestation, average weights for rural and urban women were 45.5 +/- 4.8 (SD) and 50.7 +/- 7.8 kg (P < 0.0001), respectively. Maternal weight gains over the subsequent 17 weeks for rural and urban women were 6.0 +/- 2.2 and 7.5 +/- 2.8 kg (P = 0.003) and water gains were 4.0 +/- 2.4 and 4.8 +/- 2.8 kg (P = 0.092), respectively. In both rural and urban women, birth weight was positively, and independently, associated with gestation and parity. Only for rural women, between 17 and 34 weeks, was an increase in dry mass (weight minus TBW-D2O) or a decrease in TBW-D2O as a percentage of total weight associated with a higher birth weight. At both 17 and 34 weeks, TBW-BIS increasingly underestimated TBW-D2O as the water space increased. Differences in body composition during pregnancy between rural and urban environments and possible impacts of nutrition transition on maternal body composition and fetal growth were demonstrated.