Mothers who were maltreated as children have an increased risk for giving birth to low birth weight babies. The findings, by researchers at the University of Washington, are the first to show that maternal maltreatment can affect the health of offspring.
The study also finds that childhood poverty and substance use during adolescence and pregnancy contribute to low birth weight, which is linked to infant mortality and chronic health problems.
How early-life experience affects offspring
"Our findings suggest that a mother's economic position in childhood and her experience of maltreatment during childhood have implications for her children born years later," said Amelia Gavin, lead author and assistant professor in the UW School of Social Work. "To our knowledge, this is the first study to show that maternal childhood maltreatment may lead to lower birth weight among later-born offspring."
The results were published in the Journal of Adolescent Health.
Each year about 8% of babies in the United States are born weighing less than 2,500g. Low birth weight – due to growth restriction in the womb or from being born prematurely – puts newborns at a greater risk for death before their first birthday. Babies with low birth weights who survive their first year are more likely to develop obesity, diabetes and other health risks later in life.
Low birth weight on the increase
The rate of these births has increased since the mid-1980s, even as prenatal care has improved.
"What matters most for healthy birth weight is the health status the mother brings into pregnancy," Gavin said. "We're trying to map pathways of early life exposures that lead to low birth weight."
Gavin and her co-authors examined data from an ethnically-diverse sample of 136 mothers participating in the Seattle Social Development Project since childhood. The long-term project, started by UWss Social Developmental Research Group in 1981, looks for ways to enhance positive development and reduce drug use, delinquency and risky sexual behaviours among adolescents and young adults.
Looking at mothers who had children after age 18, Gavin's analysis allowed her to see the extent to which mothers who were abused emotionally, sexually and physically before age 10 affected the birth weights of their children. She also considered the effects of childhood poverty and substance use – including binge drinking, cigarette smoking and marijuana and other drug use – during high school and pregnancy.
Maltreatment leads to substance abuse
Gavin found that maltreatment during childhood was a strong predictor of substance use during high school. And, most significantly, women who abused drugs during high school were more likely to smoke and drink alcohol during later pregnancies.
"We know that cigarette smoking and heavy alcohol use during pregnancy lead to low birth weights, and we know to warn expecting mothers about those risks," Gavin said. "Now, the results of this study show that women maltreated during childhood are more likely to use substances during pregnancy, which increases their risk of delivering low birth weight infants."
Gavin recommends that obstetric practitioners add universal screening of prospective mothers for childhood maltreatment to identify and provide services to women at risk for prenatal substance use.
"What is important about this study is that it was the mother's experience of poverty and maltreatment in childhood, not her poverty or depression or obesity in adulthood, that contributed to her infant’s low birth weight," Gavin said. - (Molly McElroy/EurekAlert!, March 2011)