Compared to babies of mothers who didn’t use cannabis before or during pregnancy, infants of those who still used it at 15 weeks had a smaller birth weight, head circumference and length. They were also born at an earlier gestational age.
This is cause for concern as these outcomes are strongly linked to future child health and development.
We saw bigger differences in these neonatal outcomes for women who used cannabis more than once a week than for those who used it less often.
We also found severe complications following birth, such as breathing problems and the need for admission to a specialist neonatal unit, were twice as likely for babies of mothers who continued to use cannabis at 15 weeks compared to babies of mothers who didn’t report using cannabis.
We’ve seen similar trends in recent studies from the United States and Canada.
Notably, we didn’t see differences in any neonatal outcomes among women who reported stopping cannabis in early pregnancy or just before becoming pregnant compared to babies of mothers who reported no cannabis use