Factors that influence the outcome of pregnancy in middle-class women.

A retrospective analysis was made of 1,080 singleton pregnancies of middle-class women to identify factors that influence outcome as measured by birth weight, gestational age, Apgar scores, and the incidence of complications. Increased birth weight was associated with increases in weight gain, maternal age, gestational age, maternal initial body weight, maternal hemoglobin and hematocrit values at 3 months, hemoglobin levels at 7 months, and socioeconomic status. For women whose initial weights were 90% to 135% of the standard, highest birth weights occurred when weight gains exceeded 29 lb. A 1 lb gain in maternal weight was associated with a 6 gm increase in birth weight. Birth weight was negatively correlated with a complicated obstetrical history and maternal cigarette smoking. Infants of heavy smokers weighed an average of 156 gm less than infants of nonsmokers. One-minute Apgar scores were significantly lower for infants of mothers who consumed alcohol and those who had had a complicated obstetrical history. Initial maternal weight and the husband's occupation positively influenced gestational age. There was no relationship between the incidence of maternal or infant complications and independent variables.