Maternal Risk-Factors In Very Low-Birth-Weight Infants

Newborns weighing under 1500 gm defy the ministrations of perinatologists and contribute heavily to the nation's high perinatal mortality rate, yet, maternal risk factors for the birth of such infants have not been analyzed separately. To determine whether maternal factors associated with the delivery of very low birth-weight infants (VLBW) under 1500 gm are different from those associated with low birthweight infants (LBW) of 1500 to 2500 gm, prenatal data on 11,114 deliveries were evaluated. The sample included 435 VLBW infants. Maternal race, age, height, weight, gravidity, parity, past pregnancy performance and present pregnancy complications were analyzed using chi-square. Factors related to an increased incidence of VLBW but not of LBW infants were: 1) maternal age ≤ 15 years, ≥ 36 years, 2) gravidity over 8, 3) previous abortions, 4) previous fetal deaths, and 5) hypertensive vascular disease/essential hypertension. Race (black) and low prepregnancy weight were not related to VLBW but were associated with an increase in LBW. The finding that low prepregnancy weight is not related to VLBW implys that limited paturient mass is not a factor in supporting a fetus up to 1500 grams. The other positive findings suggest that suboptimal reproductive capacity and preexisting hypertension predispose to the birth of a VLBW rather than an LBW infant. These results contradict the concept of a uniform set of predisposing factors for the birth of all infants weighing ≤ 2500 gm.