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Causes of low birth weight extend much further back than pregnancy
Study is first to tie low birth weight to factors three generations deep
(Chapel Hill, N.C.—August 18, 2015) – A woman’s weight at birth, education level and marital status pre-pregnancy can have repercussions for two generations, putting her children and grandchildren at higher risk of low birth weight, according to a new study by Jennifer B. Kane, assistant professor of sociology at the University of California, Irvine. The findings are the first to tie social and biological factors together using population data in determining causes for low birth weight.
“We know that low-birth-weight babies are more susceptible to later physical and cognitive difficulties and that these difficulties can sharpen the social divide in the U.S. But knowing more about what causes low birth weight can help alleviate the intergenerational perpetuation of social inequality through poor infant health,” said Kane, formerly a postdoctoral scholar at The University of North Carolina at Chapel Hill, where the research was conducted. She joined UCI in July.
Published in the June issue of the Journal of Health and Social Behavior, the study is based on both the National Longitudinal Survey of Youth 1979 and the Children of the National Longitudinal Survey of Youth 1979. The former yielded birth weights and pre-pregnancy physical and social health data on female respondents as well as social data on their mothers, while the latter captured this data on the previous survey participants’ daughters. In total, Kane looked at 1,580 mother-daughter pairs, focusing on their weight at birth, marital status and education level.
“The odds of having a low-birth-weight baby were one and a half to two times greater for mothers who themselves were born low birth weight compared to mothers who were not born low birth weight,” she said. “But also important are social factors, including education and marital status. Putting all of these factors – both intergenerational and intragenerational – together in a single model can tell us even more.”
For example, education level pre-pregnancy can be transmitted from mothers to daughters across at least three generations, and this intergenerational transmission appears to affect birth weight of future generations, Kane said.
“And knowing that biological factors perpetuate the cycle – being a low-birth-weight baby makes a woman more susceptible to delivering the same – we start to see that we can’t look at these two factors separately,” she said.
This means that causes of low birth weight extend much further back than the time frame that’s typically focused on: pregnancy. Kane’s work shows that key factors can be traced to the mother’s own early life experiences, in addition to factors dating back multiple generations.
“This really makes a difference in how we think about planning future population-level policies or programs that intend to reduce social inequalities in birth weight,” she said.
Funding for this study was provided by the Eunice Kennedy Shriver National Institute of Child Health & Human Development.
About the University of California, Irvine: Currently celebrating its 50th anniversary, UCI is the youngest member of the prestigious Association of American Universities. The campus has produced three Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 30,000 students and offers 192 degree programs. It’s located in one of the world’s safest and most economically vibrant communities and is Orange County’s second-largest employer, contributing $4.8 billion annually to the local economy.
About the University of North Carolina at Chapel Hill: The University of North Carolina at Chapel Hill, the nation’s first public university, is a global higher education leader known for innovative teaching, research and public service. A member of the prestigious Association of American Universities, Carolina regularly ranks as the best value for academic quality in U.S. public higher education. Now in its third century, the University offers 78 bachelors, 112 master’s, 68 doctorate and seven professional degree programs through 14 schools and the College of Arts and Sciences. Every day, faculty, staff and students shape their teaching, research and public service to meet North Carolina’s most pressing needs in every region and all 100 counties. Carolina’s more than 308,000 alumni live in all 50 states and 150 countries. More than 167,000 live in North Carolina.
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UNC-Chapel Hill contact: Thania Benios, (919) 962-8596, thania_benios@unc.edu
UC-Irvine contact: Heather Ashbach, (919) 824-1577, hashbach@uci.edu