Pregnant women who use marijuana more than double their odds of giving birth to a baby prematurely – about the same risk posed by having diabetes, a new international study has found.
The findings, published in the journal Public Library of Science ONE, are based on an analysis of the birth records and pot-smoking habits of more than 3,000 pregnant women in Adelaide, Australia and Auckland, New Zealand.
Researchers noted preterm or premature birth – at least three weeks before a baby's due date – can result in serious and life-threatening health problems at birth and in later life, including heart disease and diabetes.
The research team, led by Professor Gus Dekker from the University of Adelaide's Robinson Institute and the Lyell McEwin Hospital, found that the greatest risks for preterm birth included:
• A family history of low birth weight babies (six times the risk);
• Use of marijuana prior to pregnancy (more than double the risk);
• Having a mother with a history of pre-eclampsia (more than double the risk);
• Having a history of vaginal bleeds (more than double the risk);
• Having a mother with diabetes type 1 or 2 (more than double the risk);
• Mild hypertension not requiring treatment (almost 10 times the risk);
• Family history of gestational diabetes (eight times the risk);
• Receiving some forms of hormonal fertility treatment (almost four times the risk); and
• Having a body mass index of less than 20 (more than double the 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 Dekker.
"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. Our ultimate aim is to safeguard the lives of babies and their health in the longer term."