My husband smokes marijuana about twice a week and I'm starting to wonder if it is affecting our chances of conceiving.  We are coming up on our 8th month of trying to conceive and I'm a little worried.

The question of marijuana use and its impact on male fertility is an excellent question.

Marijuana has several effects, which can impair your ability to conceive a child: 

• It inhibits the release of a substance in the brain called GnRH.  GnRH normally triggers the pituitary gland to release two hormones called FSH and LH which cause the testis to make testosterone and to improve sperm production and function.  So marijuana use can directly lower testosterone levels and impair testicular sperm production.
• In a test tube, the active substance in marijuana THC was shown to impair sperm function and to impair a sperm's ability to fertilize an egg.
• Clinically, birth weight have shown to be reduced in marijuana users (even occasional users) and that in-vitro fertilization success rates are lower in marijuana users.

So, overall, forgetting about any other health reason not to smoke marijuana, when you are attempting to conceive a child, your partner (and you) should definitely not smoke marijuana.

Answered by Dr. Jonathan Schiff, M.D.