Marijuana use in pregnancy is major risk for preterm birth

http://www.eurekalert.org/pub_releases/2016-05/uoa-mui051216.php

Public Release: 12-May-2016
Marijuana use in pregnancy is major risk for preterm birth
University of Adelaide

International research led by the University of Adelaide has for the first time shown a direct link between continued marijuana use during pregnancy and pre-term birth.

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A research team led by the University of Adelaide's Robinson Research Institute considered a range of risk factors - such as cigarette smoking, age, obesity and socio-economic status - and their links to serious pregnancy complications.

The results, published online ahead of print in the journal Reproductive Toxicology, show that once all other major risk factors have been accounted for, continued marijuana use through to 20 weeks' gestation is independently associated with a five-fold increase in the risk of pre-term birth.

"Our results suggest that more than 6% of pre-term births could have been prevented if women did not use marijuana during pregnancy, irrespective of other risk factors," says lead author Professor Claire Roberts from the University's Robinson Research Institute.

"In the Australian participating center, which has a higher proportion of pregnant marijuana users, almost 12% of pre-term births could have been prevented.

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The study found that:

Among the 236 pre-term births recorded in the group, women who continued to use marijuana at 20 weeks' gestation had a significantly shorter gestation (just less than 30 weeks on average) compared with those who did not use marijuana (more than 34 weeks on average);

The proportion of very early pre-term birth was also higher, with 36% of marijuana users having delivered at less than 28 weeks' gestation and 64% at less than 32 weeks, compared with non-users: 5% at 28 weeks' gestation and 16% at 32 weeks;

The Australian participating center had the highest rate of women using marijuana before or during pregnancy (12%), followed by New Zealand (5%), Ireland (4%) and the United Kingdom (4%).

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"Anecdotally, we know that some women are using marijuana to reduce nausea in pregnancy, even though there is no medical evidence to support this. Our study was unable to determine whether there is a 'safe' time prior to 20 weeks' gestation to give up marijuana. Therefore, we recommend total abstinence from marijuana during pregnancy," she says.

tags: drug use, drug abuse