Use of cannabis during pregnancy is linked to low birthweight and the need for intensive care, reveals an analysis of the available evidence by researchers at the University of Arizona Mel and Enid Zuckerman College of Public Health and the Arizona Department of Health Services. The study is published in the online journal BMJ Open.
As cannabis becomes more socially acceptable, it is important that prospective mothers-to-be and clinicians are fully up to speed on the potential harms of using the drug during pregnancy, caution the researchers.
Cannabis remains the drug of choice in developed and developing countries with up to 5 percent of 15-64 year olds around the world thought to use it, researchers point out.
While it never used to be a major cause for concern, recent research has pointed to links between the drug and an increased risk of road traffic accidents, psychosis, HIV, hepatitis, infective endocarditis and TB. Less is known, however, about its possible effects on fetal growth and development.
The researchers carried out a comprehensive trawl of seven research databases for studies published up to 2014, looking at the effects of cannabis use during pregnancy on mother and baby up to six weeks after the birth.
Outcomes, such as anaemia in the mother, birthweight, baby’s length, need for neonatal intensive care, head circumference and early birth were all included in the review of 24 studies.
Analysis of the pooled data showed that moms-to-be who used cannabis were 36 percent more likely to have anaemia than women who did not use the drug.
Infants exposed to cannabis in the womb were 77 percent more likely to be underweight at birth and twice as likely to require intensive care as those whose moms had not used cannabis during their pregnancy.
The research in the analysis included observational studies, making it very difficult to draw firm conclusions about cause and effect. And the researchers were not able to extract data on whether any of the study participants used other illicit drugs or how much alcohol they drank — factors known to be associated with a higher risk of low birthweight and premature birth.
“There does appear to be negative consequences associated with in utero exposure to cannabis, including a decrease in birthweight and a need for placement in intensive care,” said study author Dr. Jayleen Gunn, assistant research scientist at the UA Mel and Enid Zuckerman College of Public Health.
“As the medical and social use of the drug is rapidly becoming more acceptable in the USA and around the world, understanding its effects on maternal and fetal health should become a global priority,” added Dr. Gunn.
The researchers suggest that women and their doctors could do with more information on the possible harms of using the drug during pregnancy, they say.
Prenatal exposure to cannabis and maternal and child health outcomes: a systematic review and meta-analysis
BMJ Open, 4/5/2016