IRVINE, Calif., Aug. 17 (UPI) -- Social factors such as education and marital status of a mother can have as much effect on the birth weight of her daughter as biological factors, according to research based on two long-term studies tracking mother-daughter pairs.
Researchers were aware that low birth weight can be passed down through generations of women -- a woman who is born with low birth weight is more likely to give birth to a daughter with low birth weight -- but the idea that sociological factors can have an effect as well is new.
"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," Jennifer B. Kane, assistant professor of sociology at the University of California Irvine, said in a press release. "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."
The two studies Kane used for her research -- the National Longitudinal Survey of Youth 1979 and the Children of the National Longitudinal Survey of Youth 1979 -- tracked birth weights and pre-pregnancy physical and social health data of women and the social data of their daughters. She focused specifically on birth weights, education level and marital status for 1,580 mother-daughter pairs.
Kane found that mothers who were born with a low birth weight were one and a half to two times more likely to give birth to a low-weight daughter compared to those who were born at normal weight. She said that education level pre-pregnancy can be transmitted over the three following generations and, based on the data, appears to be tied to birth weight, as well.
Typically, she said, only factors occurring during a woman's pregnancy are considered as risk factors for her baby. The new research shows that generational history can play as big a part in the health of a baby as what happens during gestation.
"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.," Kane said. "But knowing more about what causes low birth weight can help alleviate the intergenerational perpetuation of social inequality through poor infant health."
The study is published in the Journal of Health and Social Behavior.