Birth weight of US biracial (black-white) infants: regional differences.

Objective: The study examined the prevalence of low birth weight among biracial infants of black and white parents, by region of the United States.

Methods: Using the national linked live birth-death infant file for 1991, low birth weight (<2,500 g) was examined among 50,980 biracial singleton infants according to parental race (black mother-white father vs. white mother-black father).

Results: Nationally, the rate of low birth weight was 31% higher in the black mother-white father group (8.4%) than in the white mother-black father group (6.4%). The difference was smaller in the Northeast, reflecting a high rate (9.8%) for biracial infants of Puerto-Rican white mothers. The difference in the West was larger (75%), due to both a high rate in the black mother-white father group (9.1%) and a low rate for the white mother-black father group (5.2%), and persisted after controlling for parental education and a variety of maternal risk factors.

Conclusions: Further studies are needed to identify the maternal factors involved in the regional differences in the prevalence of low birth weight among biracial infants.