268 - Small for Gestational Age Across Three Generations: A Population-Based Study of Chicago Births

Poster Number: 268
Publication Number: 268.2233

Background: Small for gestational age (weight for gestational age < 10th percentile, SGA) is a well-known risk factor for infant mortality and chronic illnesses of adulthood. The limited available published data shows that African-American (AA) and non-Latina White mother’s SGA status is an independent risk factor for infant SGA (Castrillio et al, MCHJ, 2014). The degree to which this phenomenon exists across three generations is unknown.

Objective: To determine the extent to which former SGA (compared to non-SGA) women have a greater SGA birth frequency in their grandchildren; and whether the percentage of SGA infants attributable to their maternal grandmother’s (GM) SGA status differs by race.

Design/Methods: We linked the vital records of Chicago-born infants (generation-3, 2005-2017) to the previously created Illinois transgenerational birth-file of their mothers (generation-2, born 1989-1991) and maternal GM (generation-1, born 1956-1976) (David et al, 2010). Stratified and multivariable log binomial regression analyses were performed. Population attributable risk (PAR) % were calculated. Only births to African-American and non-Latina White women were studied.

Results: Former SGA women (n=1,510) had an SGA birth frequency in their grandchildren of 23.3% versus 17.6% for non-SGA women n=9,466 ), RR 1.3 (1.2, 1.5). This association existed in both races (Figure 1). There were minimal differences in the distribution of traditional high-risk maternal characteristics between infants with former SGA and non-SGA maternal GM (Table 1). The RR of SGA for infants with former SGA (compared to non-SGA) maternal GM exceeded unity across each measured maternal co-variate (Table 2). The adjusted (controlling for maternal race/ethnicity, age, education, marital status, parity, prenatal care usage, cigarette smoking) RR of infant SGA for former SGA (compared to non-SGA) maternal GM equaled 1.2 (1.1, 1.4). The PAR% of maternal GM SGA was 3% among African Americans. There were too few non-Hispanic White infants to calculate meaningful PAR%.

Conclusion(s): Maternal GM SGA status is a modest risk factor for infant SGA independent of commonly cited maternal demographic, medical, and behavioral risk factors. A small percentage of SGA African-American infants are attributable to an underlying genetic inheritance pattern. These intriguing findings have public health relevance to the long-standing racial disparity in SGA rates.