Dr. Dean

Does Marijuana Cause Birth Defects?

Posting Date: 09/07/1999

Jeri: I just found out I am pregnant, but my husband and I have been smoking a lot of marijuana and I'm worried about it causing birth defects. I've stopped smoking it now.

Dr. Dean: Well, marijuana does not seem to cause birth defects, so I think you can relax there.

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Clinically, it's difficult, because when you study women who use marijuana, there is always other stuff going on. They may be more likely to drink alcohol or take other kinds of medications.

The literature is mixed. There was one study done in Jamaica which found babies of mothers who smoked marijuana during pregnancy to be bigger and healthier, happier babies. I believe the reason there was sociodemographic - women in Jamaica who could afford to buy pot are in a group who also has healthier babies.

There was a study last week (which I didn't think was important enough to do on the air so I filed it) on the fact that there are marijuana receptors in your body - in the brain and also in the uterus and other places. And they think that marijuana may block the natural receptors and possibly could account for the reduction in blood flow and smaller babies. But that's been difficult to prove clinically, so that was just a physiological study.

The one thing they've seen clinically in mothers who smoke heavily all throughout pregnancy - which you're not going to do - is find sleep disturbances in babies when they're born. And so far, that's been the most damning thing thankfully, because a lot of women unfortunately get caught like this.