Women smoking cannabis during their pregnancies are giving birth to smaller, unhealthier babies at a higher risk of dying, researchers in Adelaide, South Australia have found.
Researchers from the University of Adelaide’s Robinson Research Institute warned the results were particularly worrying as cannabis is increasing accepted by the community as a “safe drug”.
Study leader Dr Luke Grzeskowiak said researchers tackled the effects of cannabis on neonatal outcomes, as despite it being the illicit drug most widely used by women of reproductive age in Australia, its impact was unclear.
The findings showed continued use of cannabis at 15 weeks of pregnancy was linked to babies having significantly lower birth weight, head circumference, birth length, and gestational age at birth, and also with more frequent severe neonatal morbidity or death.
“In this study, involving researchers from Australia, the UK and New Zealand, we found that continued and high frequency of cannabis use during pregnancy were both associated with significantly poorer neonatal outcomes, independent of tobacco use,” Dr Grzeskowiak said.
“Further, the frequency of severe neonatal morbidity and death was higher for babies of mothers who continued to use cannabis at 15 weeks, which is consistent with the results of a recent American study.”
Data from about 5,000 pregnant women was used by researchers, 314 of those women used cannabis either before or during their pregnancy.
The study drilled into the data to compare babies of women using cannabis up to once a week during early pregnancy and those who used cannabis more than once a week.
It found robust evidence that birth weight, length, head circumference and the infant gestational age at birth were all significantly reduced, and “the odds ratio for severe infant morbidity or death increased with persistence of cannabis use during pregnancy.”
Dr Grzeskowiak wanted the findings to be used to educate women and health care professionals about the possible harms of cannabis use during pregnancy.
“This is particularly important given the increasing perception in the community that cannabis is a safe drug,” he said.
According to the 2016 National Drug Strategy Household Survey in Australia, more than 10 per cent of women of reproductive age had used cannabis during the preceding 12 months.
“Cannabis is the most frequently used illicit drug in Australia, probably because of its increasing social and medical acceptance, as well as the recent legalisation of cannabis use in many parts of the world,” the study found.
The study captured evidence of continued cannabis use during pregnancy independent of cigarette smoking.
It observed the reduction in neonatal birth weight was comparable with that associated with continued tobacco use during pregnancy.
But there was better news for mothers to be who quit cannabis earlier.
The neonatal outcomes for those infants of women who stopped using cannabis in early pregnancy did not differ from those of mothers who had never used cannabis.
“This should be reassuring to women who used cannabis before they knew they were pregnant,” Dr Grzeskowiak said.
“How cannabis might impair neonatal outcomes is unclear, but we know that components of cannabis can cross the placenta and this raises a number of concerns about effects on child health and development.”
He called for further investigation of the potential long-term effects of cannabis use during pregnancy on child health and development.
The study included researchers from the University of Adelaide, King’s College in London, University of Auckland, University of Liverpool, University of Manchester and the University of Leeds.
It was supported by funding from the National Health and Medical Research Council and the University of Adelaide.Jump to next article