The maternal age related patterns of infant low birth weight rates among non-Latino Whites and African-Americans: the effect of maternal birth weight and neighborhood income.

To determine the age related patterns of low birth weight (<2,500 g, LBW) and small for gestational age (weight <10th percentile for gestational age, SGA) among former LBW and non-LBW White and African-American mothers. We performed stratified analyses on an Illinois transgenerational dataset of non-Latina White (n = 31,616) and African-American (n = 38,964) infants born in Chicago or Suburban Cook County (1989-1991) and their mothers (1956-1976) with appended US census income information. In both races, LBW and SGA rates were unrelated to age among former LBW 14-35 year old mothers. LBW and SGA rates decreased with advancing age only among former non-LBW White mothers (p < 0.0001). Former non-LBW 30-35 year old White women (n = 11,096) had an infant LBW rate of only 4.3 % compared to 6.8 % for their teen counterparts (n = 1,383), RR (95 % CI) = 0.6 (0.5, 0.8). In contrast, a weathering pattern of rising LBW and SGA rates with advancing age occurred only among former non-LBW African-American mothers (p < 0.0001). Former non-LBW 30-35 year old African-American mothers (N = 4,807) had a LBW rate of 15.0 % compared to 10.8 % for their teen counterparts (N = 8,627), RR (95 % CI) = 1.4 (1.3, 1.5). The same trend occurred among the subgroup of African-American mothers with an early-life and adulthood residence in impoverished neighborhoods. Maternal low birth weight does not contribute to the disparate maternal age related patterns of adverse birth outcome between the races. Moreover, it is not associated with a weathering a pattern of rising rates of LBW with advancing age among African-American mothers with a lifelong residence in impoverished neighborhoods.