Pregnant women must stay away from marijuana or cannabis as it could increase the risk of preterm births by five-fold, warns a new study.
"The results suggest that more than six percent of pre-term births could have been prevented if women did not use marijuana during pregnancy, irrespective of other risk factors," said lead study author Claire Roberts from Adelaide's Robinson Research Institute.
The team analyzed more than 5,500 pregnant women from Australia, New Zealand, Ireland and Britain.
The results found that the Australian participating center had the highest rate of women using marijuana before or during pregnancy 12 percent, followed by New Zealand five percent, Ireland four percent and Britain four percent.
"Continued marijuana use in pregnancy has been independently linked to pre-term birth. Based on our findings, we consider marijuana to be a major public health concern for pregnant women and their babies," Roberts added in the paper published in the journal Reproductive Toxicology.
The proportion of very early pre-term birth was also higher, with 36 percent of marijuana users having delivered at less than 28 weeks' gestation and 64 percent at less than 32 weeks,
The study was unable to determine whether there is a 'safe' time prior to 20 weeks' gestation to give up marijuana. "But we recommend total abstinence from marijuana during pregnancy," Roberts stated.