TUESDAY, July 30, 2025 — A new study found that heavy alcohol consumption is associated with an increased risk of unintended pregnancy, while cannabis use does not appear to affect contraceptive effectiveness.
The research, published in the journal Obstetrics & Gynecology, followed 3,943 women aged 18-40 over 12 months. Participants used various contraceptive methods including pills, intrauterine devices (IUDs), and implants.
Key findings showed:
- Women consuming more than three alcoholic drinks daily had a 50% higher risk of contraceptive failure compared to non-drinkers
- No significant association between cannabis use and pregnancy rates
- Smoking tobacco also showed no impact on contraceptive effectiveness
Lead author Dr. Kari Stephens from Baylor University noted that the study couldn't determine causation, but suggested alcohol might interfere with contraceptive adherence. "Heavy drinkers may be more likely to forget doses or experience vomiting that prevents proper absorption," she explained.
The research team recommended healthcare providers should consider discussing alcohol consumption patterns during contraceptive counseling. However, they emphasized that the observational study couldn't establish direct cause-and-effect relationships, and called for further research on how substance use interacts with different contraceptive methods.
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