Father’s Cannabis Use Could Double Risk of Miscarriage.

Male cannabis use before conception could double the risk of miscarriage, according to School of Public Health research presented at the 75th Scientific Congress of the American Society for Reproductive Medicine on October 14.

The research is pending peer review and publication, but is the first study to link male cannabis use and pregnancy issues. Previous research has suggested that frequent cannabis use reduces semen quality.

“This is just one study, and more research is needed before any concrete recommendations for couples are made,” says doctoral candidate Alyssa Harlow, who led the study. “It’s important that we continue to do research that helps us better understand the health impact of cannabis, including on our reproductive health, so that couples can make informed decisions.”

Harlow and colleagues used data from the SPH-based Pregnancy Study Online (PRESTO) of over 1,400 couples throughout North America. Couples who are trying to conceive answer a variety of questions as part of PRESTO—including questions about behaviors such as cannabis use—every two months until conception and then at various stages of pregnancy.

After controlling for the couples’ other behavioral and medical information collected in PRESTO (including the women’s cannabis use), the researchers found that couples where the man used cannabis no more than once a week in the two months before conception were 1.07 times as likely to miscarry as couples where the man did not use cannabis, while couples where the man used cannabis more than once a week were 2.04 times as likely to miscarry.

In a previous study, the researchers found that cannabis use by either partner did not affect the chances of a couple conceiving.

The other SPH co-authors were Amelia Wesselink, a postdoctoral associate in epidemiology; and Kenneth Rothman, Elizabeth Hatch, and Lauren Wise, professors of epidemiology.

—Michelle Samuels

PRESTO is still enrolling participants. Learn more.