ANN ARBOR, Mich.---Birth weight has significant and lasting effects, a new study finds. Weighing less than 5.5 pounds at birth increases the probability of dropping out of high school by one-third, reduces yearly earnings by about 15 percent and burdens people in their 30s and 40s with the health of someone who is 12 years older.
The study, presented May 22 in Washington, D.C. at the National Summit on America's Children, is the first to link birth weight with adult health and socioeconomic success using a full, nationally representative sample of the U.S. population. It is based on an analysis of more than 35 years of data on more than 12,000 individuals from the Panel Study of Income Dynamics, conducted since 1968 by the University of Michigan Institute for Social Research (ISR).
Funded by the National Institute on Aging, the analysis includes data from the original study families, plus their descendants who have gone on to form families of their own. Because of the study's unique genealogical design, the researchers were able to compare outcomes for siblings to isolate the impact of low birth weight apart from other common family conditions siblings share.
According to the authors, economists Rucker Johnson at the University of California, Berkeley, and Robert Schoeni at U-M, the study provides the most detailed look to date at how well-being and disadvantage are transmitted across generations within families.
"The poor economic status of parents at the time of pregnancy leads to worse birth outcomes for their children," Johnson and Schoeni write in a working paper from the U-M National Poverty Center. "In turn, these negative birth outcomes have harmful effects on the children's cognitive development, health, and human capital accumulation, and also health and economic status in adulthood. These effects then get passed on to the subsequent generation when the children, who are now adults, have their own children."
Among the key findings:
The ISR Panel Study on Income Dynamics is funded primarily by the National Science Foundation, the National Institute on Aging, and the National Institute on Child and Human Development. The study is co-directed by Schoeni and U-M economist Frank Stafford.
Established in 1948, the University of Michigan Institute for Social Research (ISR) is among the world's oldest academic survey research organizations, and a world leader in the development and application of social science methodology. ISR conducts some of the most widely-cited studies in the nation, including the Reuters/University of Michigan Surveys of Consumers, the American National Election Studies, the Monitoring the Future Study, the Panel Study of Income Dynamics, the Health and Retirement Study, and the National Survey of Black Americans. ISR researchers also collaborate with social scientists in more than 60 nations on the World Values Surveys and other projects, and the Institute has established formal ties with universities in Poland, China and South Africa. ISR is also home to the Inter-University Consortium for Political and Social Research (ICPSR), the world's largest computerized social science data archive. Visit the ISR web site at www.isr.umich.edu for more information.
Established in 2002, the National Poverty Center (NPC) is a nonpartisan research center located within the U-M Gerald R. Ford School of Public Policy. The Center conducts and promotes multi disciplinary, policy-relevant research on the causes and consequences of poverty and provides mentoring and training to young scholars. For more information, visit the NPC website at http://www.npc.umich.edu
For more information:
--U-M Institute for Social Research: www.isr.umich.edu
--ISR Panel Study of Income Dynamics: http://psidonline.isr.umich.edu
--U-M National Poverty Center: http://www.npc.umich.edu/
--Working paper from the U-M National Poverty Center: http://www.npc.umich.edu/publications/working_papers/?publication_id=117& ).