Timing of the influence of maternal nutritional status during pregnancy on fetal growth

This study, which used data from a longitudinal nutrition study of mothers and infants in rural Guatemala, tested a hypothesis that the influence of maternal nutritional status on various measurements of fetal growth is trimester-specific. The relationships between various measures of newborn size and the changes of maternal anthropometry at various stages of pregnancy were analyzed by ordinary least squares multiple regression techniques. The sample included 235 mother-infant pairs who had complete anthropometry for both the newborns (weight, length, and head circumference) and their mothers at 3, 6, and 9 months of pregnancy (weight, height, circumferences of mid-upper arm and thigh, skinfold thicknesses at biceps, triceps, calf, thigh, and subscapular sites). Each kilogram of maternal weight gain in the second and third trimester was associated with statistically significant increases in birth weight of 62 g (P < 0.001) and 26 g (P < 0.05), respectively. Newborn length and head circumference were significantly associated with maternal weight gain and the changes in maternal thigh skinfolds in mid-pregnancy only. The overall results suggest that maternal nutritional status in mid-pregnancy rather than in late pregnancy is a more important determinant of fetal growth in weight, length, and head circumference. Am. J. Hum. Biol. 10:529-539, 1998. © 1998 Wiley-Liss, Inc.