The Washington State Intergenerational Study of Birth Outcomes: methodology and some comparisons of maternal birthweight and infant birthweight and gestation in four ethnic groups

A statewide database of vital records and hospital discharge summaries of obstetric and neonatal admissions for Washington State in 1987–95 was linked to the birth certificates of mothers born in the state. A total of 46 000 births to mothers of four racial/ethnic groups were studied: Whites, African‐Americans, Native Americans and Hispanics. For all four groups inverse associations were found between maternal birthweight and infant low birthweight and preterm birth. The birthweight distribution of African‐American mothers was displaced markedly downwards compared with the Whites; this difference in maternal birthweight is offered as a partial explanation of the greater prevalence of suboptimal pregnancy outcomes in the former. In contrast, the maternal birthweight distributions of Whites, Native Americans and Hispanics are similar; differences in pregnancy outcomes are probably more related to maternal preconceptional and postnatal factors in these groups as well as differences in pregnancy‐related factors. Mothers’ birthweight may have clinical value in identifying high‐risk pregnancies.