Trying to get pregnant? Don't use cannabis

Researchers at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development studied conception rates among more than 1,200 women attempting to get pregnant and who had suffered one or two miscarriages in the past. Five percent of the women – 62 in total – either reported using cannabis while trying to conceive or urine tests showed they'd been using the drug.

The women who used cannabis – either marijuana or hashish – in the weeks prior to pregnancy were 40 percent less likely to conceive than women who did not use cannabis. The researchers followed the women through a maximum of six monthly cycles. Cannabis users also had differences in ovulation-related reproductive hormones compared to non-users, the researchers noted in the journal Human ReproductionOpens a new window.

For women who did get pregnant, the researchers did not find any difference in miscarriage rates between those who used cannabis and those who didn't.

The study findings suggest cannabis could interfere with women's ability to conceive. For example, animal studies have shown that cannabis may change the lining of the uterus and make it more difficult for an embryo to implant. However, the number of women in the study who used cannabis was small, and more research is needed to confirm the findings.

Still, the researchers advise women to be cautious about using cannabis if trying to get pregnant. Likewise, most experts agree it's best to avoid marijuana products if you get pregnant as well, because it's been linked to several birth and health problems including preterm birth, placental abruption, irritability in newborns, and developmental challenges in children.

Find out more about the possible dangers of weed use during pregnancy. And if you're not using marijuana but still struggling to conceive, check out our guidance on how to get pregnant fast.