Marijuana doubles risk of preterm birth
MARIJUANA use prior to pregnancy more than doubles the risk of a preterm birth, according to a new Australian-led study.
Researchers collected demographic and health-related data from more than 3000 pregnant women in Australia and New Zealand in 2004–08, to assess the biggest risk factors associated with birth prior to 37 weeks gestation.
They found that a family history of low birth weight babies was the strongest risk factor for preterm birth. Women with such a history were more than 5.5 times likely to have a premature baby.
Marijuana use prior to pregnancy was the second highest risk factor and women who smoked marijuana before they were pregnant were almost 2.5 times more likely to deliver preterm.
“We are unable to determine whether this association is due to a toxic effect of marijuana or is a marker of a suite of lifestyle factors that contribute to the risk,” the authors wrote.
Having a mother with a history of pre-eclampsia and having a history of vaginal bleeds, also more than doubled the chances of a premature delivery.
The team also examined the risk factors associated with the preterm rupture of membranes leading to birth.
Women with mild hypertension had a ten-fold increased risk of preterm membrane rupture, while women with a family history of recurrent gestational diabetes had an eight-fold greater risk.
“Our study has found that the risk factors for both forms of preterm birth vary greatly, with a wide variety of health conditions and histories impacting on preterm birth," said Professor Gustaaf Dekker, from the University of Adelaide's Robinson Institute and the Lyell McEwin Hospital.
“Better understanding the risk factors involved in preterm birth moves us another step forward in potentially developing a test – genetic or otherwise – that will help us to predict with greater accuracy the risk of preterm birth.”