Can One Drink During Pregnancy Cause Fetal Alcohol Syndrome?
No safe threshold of alcohol use during pregnancy has been established, and therefore any amount of alcohol—including a single drink—poses potential risk to the developing fetus and should be completely avoided. 1, 2
The Evidence on Safe Alcohol Thresholds
The CDC and National Task Force on FAS/FAE explicitly state that because no safe threshold of alcohol use during pregnancy has been established, women who are pregnant, planning a pregnancy, or at risk for pregnancy should not drink alcohol. 1 This recommendation is based on the inability of research to identify any amount of alcohol that is definitively safe for fetal development.
The American Academy of Pediatrics reinforces this position with clear guidance that:
- No amount of alcohol intake should be considered safe during pregnancy 3
- There is no safe trimester to drink alcohol 3
- All forms of alcohol (beer, wine, liquor) pose similar risk 3
- Binge drinking poses dose-related risk to the developing fetus 3
Understanding the Risk Spectrum
While a single drink is unlikely to cause the full constellation of features required for a FAS diagnosis (which requires characteristic facial dysmorphology, growth restriction, and CNS dysfunction), 4 prenatal alcohol exposure causes a broad range of adverse developmental effects that fall under the umbrella term Fetal Alcohol Spectrum Disorders (FASD). 3
The key clinical concern is that alcohol is a definite teratogen, 5 and its effects on the fetus include:
- Reactive oxygen species generation and mitochondrial damage 6
- Disrupted neuronal cell-cell adhesion 6
- Placental vasoconstriction 6
- Epigenetic effects 6
- Neurocognitive and behavioral problems that are lifelong 3
Why We Cannot Identify a "Safe" Single Drink
The amount of alcohol that can be safely consumed during pregnancy has yet to be identified, 5 and multiple factors influence fetal vulnerability:
- Differences in maternal and fetal enzymes allow alcohol to have prolonged effects on the fetus 6
- Genetic influences affect susceptibility 6
- Timing of exposure during pregnancy matters 6
- Individual variation in metabolism and placental function creates unpredictable risk 6
Because we cannot predict which pregnancies will be affected by even minimal alcohol exposure, the only evidence-based recommendation is complete abstinence. 3, 4
Clinical Implications
Alcohol-related birth defects and developmental disabilities are completely preventable when pregnant women abstain from alcohol use. 3 This makes universal screening and counseling essential:
- All women of childbearing age should be screened for alcohol use 1, 7
- Brief interventions using motivational interviewing significantly reduce alcohol consumption during pregnancy 7
- Women who have consumed alcohol early in pregnancy before knowing they were pregnant should be counseled about complete abstinence going forward 4
Common Pitfall to Avoid
Do not reassure patients that "one drink won't hurt" or that occasional light drinking is acceptable. While full FAS requires substantial exposure, the threshold for neurodevelopmental effects and other components of FASD remains unknown. 3, 4 The precautionary principle demands complete abstinence given that these effects are entirely preventable. 3