Low Birth Weight and Parental Investment: Do Parents Favor the Fittest Child?

Do parents contribute to birth weight disparities in status attainment? This study uses a nationally representative sample of 8,550 children and 1,450 twins from the Early Childhood Longitudinal Study-Birth Cohort to investigate whether, as recent studies have suggested, parents favor healthier children. Children with poor health are found to receive fewer parental investments, including breastfeeding and quality parent- child interaction, but results from between- and within-family regression models, using low birth weight as a proxy for child health, find no evidence that parents compensate for or reinforce child health endowments. Instead, birth-weight disparities in parental investment are linked with observable family, maternal, and child sociodemographic characteristics. Our results raise doubts about the utility of human capital models to explain health disparities in parental investment and shed new light on the broad spectrum of disadvantage faced by children with poor health.Key Words: birth weight, child health, ECLS-B, human capital, parental investment, twinsDo parents favor their healthiest children? Even the suggestion is disturbing to many, yet ' 'normal-birth-weight children are 5% -11 % more likely to receive early childhood parental investments than their low-birth-weight siblings" (Datar, Kilburn, & Loughran, 2010, p. 145). Parental investments-which broadly include economic resources, quality attention, and social interaction-structure children's social, educational, and occupational outcomes by providing a beneficial learning environment and access to resources that develop life-long human capital accumulation (Becker, 1964; Blau & Duncan, 1967; Yeung, Lin ver, & BrooksGunn, 2002). Much of the research on the determinants of child health disparities in educational and occupational attainment has focused on biological and socioeconomic explanations (Palloni, 2006), but a strand of economic theory suggests that birth weight disparities in life chances emerge within the home. Using a sample of children and twin siblings from the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B), our study builds on this research by investigating whether parents, seeking to maximize an economic return, contribute to health disparities, or whether patterns of parental investment by health status, like other parenting practices, are closely linked with variation in family socioeconomic status (SES).Why might one child receive more parental investment than another? Explanations for variation in parental investment by child health endowment focus on three possible associations. Parents may reinforce disadvantages by investing fewer resources in children with poor health, parents may reinforce endowments by investing greater resources in children with better health, or variation in parental investment by health endowment may be primarily shaped by cultural norms and parents' access to resources.Becker and Tomes's (1976) family wealth model argues that parents, in an effort to maximize a return on human capital investment, tend to reinforce endowments by investing more resources in better endowed children-where endowments are broadly defined as traits, physical appearance, health status, and temperament. Previous research has found variation in parental investment across multiple measures of endowments, including gender (Hopcroft, 2005), biological and nonbiological children (Downey, 1995; Hamilton, Cheng, & Powell, 2007), and physical attractiveness (Clifford & Walster, 1973). To the extent that birth weight is a reasonable proxy for physical endowments associated with success and achievement later in the life course (Case, Lubotsky, & Paxson, 2002; Haas, 2006), at least two studies have found that parents reinforce the disadvantages of low birth weight by allocating fewer resources toward poorly endowed, less healthy children (Becker & Tomes, 1976; Datar et al., 2010). …