Cannabis Hampers Baby Growth
8 January 2002
Researchers at the University of Bristol have found that pregnant women who frequently use cannabis during their pregnancy may affect the growth of their unborn child.
Researchers at the University of Bristol have found that pregnant women who frequently use cannabis during their pregnancy may affect the growth of their unborn child. With the recent change in status of cannabis from a class A to class B drug, it is important to assess whether it is entirely safe for use during pregnancy. A marker which often indicates an effect on the unborn child is the baby's weight at birth.
The findings were announced by Kate Northstone, from the Children of the 90s project, also known as ALSPAC (Avon Longitudinal Study of Parents and Children). This study based in Bristol, has monitored the health and development of over 14,000 children from pregnancy.
Mrs Northstone said, "we have found a small reduction in birthweight in those babies whose mothers smoked cannabis at least once a week before and during their pregnancy".
The researchers found that 5% of mothers had used cannabis at some time before they became pregnant, this reduced to less than 3% whilst pregnant. The women who smoked cannabis had similar characteristics to those women that are already known to be most at risk of having babies with low birthweight: younger and first time mothers and those who use other substances such as alcohol and tobacco. In the Bristol study, almost 70% of cannabis users also smoked regularly. The adverse effects of smoking on birth weight are well known, but the association between cannabis use and lower birthweight was still evident after taking smoking and a variety of other factors into account.
Long term follow up of the children will determine whether there are any adverse effects on the child's development. Until such a time as the results are available, the Bristol scientists recommend that pregnant women should be encouraged to avoid all forms of substance use while they are pregnant.
"Maternal use of cannabis and pregnancy outcome". DM Fergusson, LJ Horwood, K Northstone and the ALSPAC Study Team. British Journal of Obstetrics and Gynecology. doi: 10.1111/j.1471-0528.2002.01020.x
ALSPAC The Avon Longitudinal Study of Parents and Children (also known as Children of the 90s) is a unique ongoing research project based in the University of Bristol. It enrolled 14,000 mothers during pregnancy in 1991-2 and has followed most of the children and parents in minute detail ever since.