Birth weights of infants of black and white mothers without pregnancy complications.

An analysis of 10,159 normal spontaneous vaginal deliveries was performed to examine racial differences in mean birth weight of infants whose mothers were without antepartum or intrapartum medical complications of pregnancy. The study was limited to black and white infants of low-income mothers who were inborn, singleton, and weighed greater than or equal to 500 gm at birth. High-risk maternal transfer patients and patients with hypertension, toxemia, bacteriuria, pyelonephritis, renal failure, diabetes, anemia, polyhydramnios, oligohydramnios, prolapsed cord, vaginal bleeding, placenta previa, abruptio placentae, prolonged rupture of membranes, maternal fever on admission, amnionitis, sexually transmitted diseases, or fewer than five prenatal care visits were excluded. When statistically significant differences in demographic characteristics were controlled, black infants had an average birth weight 181 gm less than that of white infants.