Relax…  cannabis use does not cause premature birth or low birth weight

There has been quite a bit of talk about the use of cannabis by expecting mothers recently highlighting past study results which linked cannabis use to low birth weights and premature births. A study has been published online in the Obstetrics and Gynecology journal showing that cannabis use alone by expectant mothers is not associated with an increased risk of birth defects such as low birth weight and premature birth. For the study, researchers reviewed and analyzed data gathered from 31 studies involving 7,800 women who reported using cannabis during their pregnancy as well as an additional 124,000 mothers who had not smoked marijuana while pregnant.

When they initially looked at the data, researchers found that women who smoked cannabis while they were pregnant carried a 43 percent risk of delivering a child with low birth weight and that their chances of giving birth prematurely increased by 32 percent. But when they adjusted their pooled data to account for tobacco use and other "confounding factors," researchers found that there was no statistically significant increased risk for low birth weight when only marijuana was used. When tobacco and cannabis were both used, researchers found that mothers were 85 percent more likely to have a preterm birth than those who did not use marijuana or tobacco. They also found that cannabis use did not increase risk of miscarriage or stunted gestation.

The researchers concluded that "Maternal marijuana use during pregnancy is not an independent risk factor for adverse neonatal outcomes after adjusting for confounding factors. Thus, the association between maternal marijuana use and adverse outcomes appears attributable to concomitant tobacco use and other confounding factors. "

The researchers conducting the study at the Washington University School of Medicine in St. Louis, Missouri have reportedly stated that findings in their study "do not imply that marijuana use during pregnancy should be encouraged or condoned." The study did not explore any possible long-term effects on the health of babies born to mothers who used cannabis during their pregnancy.