New York, Aug 18 (IANS): Social factors such as a woman's education level and marital status before pregnancy can affect birth weight of her daughters and granddaughters, a new study says.

The study 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," said researcher Jennifer Kane, assistant professor of sociology at the University of California, Irvine in the US.

"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," Kane noted.

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 cannot 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 is typically focused on: pregnancy.

The findings tie social and biological factors together in determining causes for low birth weight.
"Knowing more about what causes low birth weight can help alleviate the intergenerational perpetuation of social inequality through poor infant health," Kane noted.

The study was published in the Journal of Health and Social Behaviour.