The limited available data has been unable to delineate the relation of parental birth weight to the unexplained race differential in infant LBW rates. We analyzed a transgenerational dataset of Illinois vital records to determine the public health impact of maternal and paternal LBW on race-specific infant LBW rates. The infant generation consisted of all African-Americans and whites born in Illinois between 1989-1991. The parent generation included mothers and fathers who were born in Illinois between 1956-1975. In the infant cohort, the LBW rate was 11.7% for African-Americans(N=15,287) compared to 5.0% for whites (N=117,708). In the parent cohort, the LBW rate was 10.9% among African-Americans and 4.9% among whites. Within the African-American population, the LBW rate was 17.9% among infants born to LBW mothers compared to 10.8% for infants born to non-LBW mothers; RR=1.8(1.6-1.9). Within the white population, the LBW rate was 8.5% among infants born to LBW mothers compared to 4.8% for infants born to non-LBW mothers; RR=1.7 (1.6-2.0). In both races, a weaker association was observed between paternal and infant birth weight: RR=1.3 (1.1-1.5) and 1.2 (1.0-1.3), respectively. Reflecting the greater prevalence of LBW among African-American parents, the population attributable risk percentage (PAR%) of parental LBW was 10.3% for African-Americans compared to 3.6% for whites (Table).

Table 1
Full size table

We conclude that 1) maternal birth weight has a stronger impact on infant birth weight than paternal birth weight, and 2) a greater proportion of LBW African-American (compared to white) births are attributable to parental LBW.