A study has found that women who drink excessively have a significantly increased risk of unintended pregnancy. While both can cause loss of consciousness, marijuana does not increase the risk of unintended pregnancy. This means alcohol is more dangerous than drugs for contraception.
Dr. Sarah Raifman of the University of California, San Francisco (UCSF) medical school's obstetrics and gynecology department released these findings on the 31st (local time) in the international journal "Addiction."
The research team surveyed over 2,000 women aged 15 to 34 and selected 936 who stated they did not want to become pregnant. Among them, 429 were classified as excessive drinkers based on standard alcohol screening criteria, and 362 reported using marijuana. 157 reported using marijuana daily or nearly every day.
Both excessive drinkers and marijuana users exhibited a stronger average desire to avoid pregnancy, but they showed differences in actual pregnancy rates. Women who drank heavily and did not desire pregnancy were found to be 50% more likely to become pregnant than others. In contrast, those who smoked marijuana did not have a higher likelihood of unintended pregnancy.
As a result of a year-long follow-up, 71 out of 936 became pregnant, of whom 38 (about 54%) were excessive drinkers. This is a higher number than the pregnancy rate combined for women who drank moderately or not at all. Conversely, among marijuana users, 28 women became pregnant, which was not significantly higher than non-users.
Women who drink heavily can have a detrimental impact on the fetus if they become pregnant unintentionally. Dr. Raifman, the first author of the paper, noted, "Fetal Alcohol Spectrum Disorders (FASD) are serious conditions that affect the fetus due to the mother's drinking, and the risk increases with the amount and duration of alcohol consumed. Women who suspect an unintended pregnancy should receive proactive intervention from healthcare professionals to stop drinking immediately."
References
Addiction(2025), DOI: https://doi.org/10.1111/add.70135