Influence of maternal birth weight on rate of fetal growth and duration of gestation.

Birth certificates of infants born in Tennessee during 1979 to 1984 were linked with the birth certificates of their mothers, who were born in Tennessee during 1959 to 1966 (n = 43,891) to study the association between maternal and infant birth weights. A highly significant association (P less than 0.0001) between maternal and infant birth weights was found for both blacks and whites. Women who weighed 4000 to 4499 g at birth were at lowest risk for delivery of a small for gestational age (SGA) infant (5.9% for whites, 4.8% for blacks). The risk of giving birth to an SGA infant increased with decreasing maternal birth weight, reaching a maximum of 19.8% for white mothers who weighed 2000 to 2499 g at birth, and 20.0% for black mothers who weighed 1000 to 1499 g at birth. In contrast, the rate of preterm birth varied much less by maternal birth weight for both whites and blacks. These data suggest that maternal birth weight exerts a stronger influence on intrauterine growth than on the duration of gestation. Women who were smaller than average at birth should be considered at high risk for delivery of an SGA infant.