Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital.
Furthermore, the effects of marijuana on fertility seem to accumulate over time. This means that although teenage girls who smoke marijuana are more likely to get pregnant, by the time a chronic marijuana smoking woman is in her mid-twenties, she may be more likely to experience a delay in getting pregnant.
Quitting marijuana can be harder than many long-term marijuana users expect, so you and your partner would be wise to quit as soon as possible, while you still have time to get help before getting pregnant. If either or both parents still use marijuana when the baby arrives, you are increasing the risk that your child may use drugs in the future, and parental drug use is implicated in many difficulties for children and families.
Obviously, if you are both smoking marijuana, you risk increasing the chances of infertility as a couple.
Research suggests that marijuana can negatively affect female fertility in the following ways:
Another study in 1992 (Vescovi et al.) found that levels of luteinizing hormone(LH), an important pituitary gland hormone involved in reproductive function, were reduced in male chronic cannabis users compared to a non-cannabis-using, age-matched control group. A previous 1986 study (Cone et al.) also found a significant reduction in LH levels immediately after smoking cannabis.
Other studies seen as providing evidence that cannabis use can cause foetal abnormalities are animal studies (Geber & Schramm 1969, Phillipset al, 1971) in which rabbits, hamsters, rats and mice were injected with vast doses of crude cannabis extract (as much as 666mg/kg in one instance!). Such massive doses of cannabis would be practically impossible for a human to consume through conventional means, and are essentially useless as a point of comparison.
For healthy adult males, it seems that use of THC does indeed cause some negative effects on fertility, which tend to increase with higher doses. However, THC’s endogenous analogue anandamide appears to be critical to the functioning of the male reproductive system.
While the effect of cannabis use on male fertility appears to be quite straightforward—with male chronic cannabis users being likely to experience some degree of impairment to reproductive physiology—the effect on the human female reproductive system is less clear-cut.
Female reproductive health is vastly complex in itself, as it not only comprises the ability to become pregnant but also the ability to carry healthy offspring to term and successfully give birth.
Burkman’s team studied only men. But she says that when women smoke marijuana, the active ingredient — THC — appears in their reproductive organs and vaginal fluids. Sperm exposed to this THC are likely to act just as sperm exposed to THC in the testes.
“Marijuana-smoking men’s sperm are hyper. They are way out there,” Burkman tells WebMD. “They already have begun the vigorous swimming called hyperactivation. Sperm should be quiet at first. They should be waiting to be washed into cervix and approach the egg before they start hyperactivation.”
The smokers weren’t the only ones who got high. The drug affected their sperm, too. These stoned sperm party hard. And then? They burn out, researchers say.
Marijuana and Fertility Timing
“It is not a head start. They are going to blow it,” Burkman says. “They’re too fast, too early. Each individual sperm can maintain this swimming only so long, only several hours. Then it poops out. If it has run out of hyperactivation before it gets close to the egg, it will not fertilize. These sperm are going to burn out.”
“The reason men have millions of sperm is because the fertility process is more difficult than people think,” Dominguez tells WebMD. “The whole process of ascending up the tract to the fallopian tubes and then finding the egg is delicately balanced.”
Burkman announced the findings at this week’s meeting of the American Society of Reproductive Medicine.
“The marijuana-smoking men had significantly lower semen volume,” Burkman says. “Many had pretty low volume, about half the male norm. If they came to our clinic as patients, we’d tell them they are abnormal. . They are delivering significantly fewer sperm to the female when they have sexual intercourse.”