Race and birthweight in biracial infants.

OBJECTIVES. The purpose of the study was to determine the role of infant race as a determinant of the Black-White disparity in low birthweight (< 2500 g). METHODS. Univariate analysis and multivariate logistic regression were performed on Illinois vital records from 1982 and 1983 and on 1980 United States census income data. RESULTS. Fourteen percent of the infants born to Black mothers and White fathers were of low birthweight, compared with 9% of infants born to White mothers and Black fathers and 6% of a random sample of White infants. Both groups of biracial infants were more likely to have been born to unmarried mothers and to reside in very low-income (< $10,000 per year) census tracts than were White infants. When all confounding variables were entered into a logistic model, the adjusted odds ratio of low birthweight for biracial infants born to Black mothers and White fathers equaled 1.4. When biracial infants born to White mothers and Black fathers were compared with White infants, the adjusted odds ratio of low birthweight equaled 1.0. CONCLUSIONS. Paternal and consequent infant race does not affect the birthweight distribution of those born to White mothers and Black fathers. Unidentified factors closely related to maternal race underlie the Black-White disparity in infant birthweight.