The short answer: before you get pregnant, if possible. There is no known safe amount of alcohol at any point during pregnancy, and every major health organization, including the CDC and the World Health Organization, recommends complete abstinence from the moment you could be pregnant through delivery. If you’re already pregnant and still drinking, stopping now still makes a meaningful difference for your baby’s development.
The Official Recommendation Is Zero Alcohol
The CDC states it plainly: there is no safe amount of alcohol use during pregnancy, and there is no safe time during pregnancy to drink. The WHO echoes this, noting that no form of alcohol consumption is risk-free. This isn’t a conservative estimate with a hidden safe threshold underneath. It reflects the fact that researchers have never been able to identify a level of drinking that carries zero risk to a developing baby. Even low levels of maternal alcohol consumption have been linked to behavioral problems in children at ages six and seven.
Both organizations also emphasize that abstinence should ideally begin before conception. If you’re actively trying to get pregnant, stopping alcohol use while you’re still trying protects your baby during the earliest days of pregnancy, a period when most women don’t yet know they’ve conceived.
Why Preconception Matters
About half of all pregnant women drink alcohol in the three months before finding out they’re pregnant, and 60% of frequent drinkers don’t realize they’re pregnant until the fourth week of gestation. That means many pregnancies have several weeks of unintentional alcohol exposure simply because of timing. The first weeks after conception are when the embryo’s organs, limbs, and facial structures begin forming. Alcohol exposure during this window can interfere with that process.
This is why the recommendation extends to anyone who could become pregnant, not just those who’ve confirmed a pregnancy. If you’re sexually active, not using contraception, and drinking regularly, the safest approach is to stop drinking before a positive test rather than after one.
What Alcohol Does to a Developing Baby
When a pregnant person drinks, alcohol crosses the placenta and reaches the fetus directly. The developing baby processes alcohol far more slowly than an adult, so it stays in the baby’s system longer.
Research shows that alcohol disrupts the placenta’s ability to deliver glucose and other nutrients. It essentially reprograms how the placenta handles sugar and fat metabolism. The placenta’s blood vessels constrict, reducing blood flow and limiting the fuel available for fetal growth. What makes this especially concerning is that the effects are selective: in animal studies, alcohol exposure reduces fetal brain weight without necessarily reducing body weight. The baby’s body may look fine, but the brain is underfed. The fetus attempts to compensate by producing its own glucose, but this backup system isn’t enough to support normal brain development, which can lead to lasting cognitive and learning deficits.
The Brain Develops the Entire Pregnancy
One reason there’s no “safe trimester” for drinking is that the fetal brain grows throughout all nine months. Early pregnancy is when the basic brain structure forms. The second trimester involves rapid growth of brain cells. The third trimester is when the brain’s surface folds develop and neural connections multiply. Alcohol can cause damage at every one of these stages, just in different ways.
This is also why the CDC emphasizes that it is never too late to stop. If you drank during the first trimester before learning you were pregnant, stopping now still protects your baby during the remaining months of brain growth. Each week without alcohol exposure is a week of healthier development.
Fetal Alcohol Spectrum Disorders
Prenatal alcohol exposure is the leading cause of preventable developmental disabilities. The umbrella term for these conditions is fetal alcohol spectrum disorders (FASDs), and up to 1 in 20 U.S. school-aged children may be affected. That range spans from the most severe form, fetal alcohol syndrome (FAS), which involves physical differences and significant intellectual disability, to subtler conditions that show up primarily as learning and behavioral challenges.
Children with FASDs can experience a wide range of lifelong difficulties:
- Learning and memory problems, including trouble retaining material they’ve already been taught
- Attention and focus issues, often resembling ADHD
- Poor reasoning and impulse control, which affect judgment in social situations
- Speech and language delays
- Difficulty with math, which is one of the most consistently affected academic areas
- Behavioral challenges, including severe tantrums, irritability, and trouble shifting between tasks
- Trouble with daily living skills like dressing appropriately, bathing, and navigating social play
These aren’t problems children simply outgrow. FASDs are permanent, though early intervention can help manage symptoms. The WHO also notes that alcohol during pregnancy increases the risk of miscarriage, stillbirth, and premature delivery, adding physical complications on top of developmental ones.
If You Drank Before You Knew
This is one of the most common concerns, and it’s worth addressing directly. Many women have a few drinks in the weeks before a positive pregnancy test. If that’s your situation, the most important thing is what you do from this point forward. The CDC’s message is clear: it is never too late to stop, and stopping at any point improves your baby’s health and well-being.
Very early in pregnancy, before the embryo has implanted in the uterine wall (roughly the first two weeks after fertilization), the developing cluster of cells is not yet sharing a blood supply with the mother in the way it will later. This doesn’t mean early drinking is harmless, but it does mean that many women who drank before a missed period go on to have healthy pregnancies once they stop. The key is to stop as soon as you know and not to let guilt about past weeks prevent you from making the best choice going forward.
Practical Steps for Stopping
If you drink socially and are planning a pregnancy, tapering off or stopping before you start trying to conceive is the simplest approach. Switch to non-alcoholic alternatives at events, and let your partner know so they can support you.
If you drink more heavily and find it difficult to stop, that’s a medical situation, not a moral failing. Abruptly quitting heavy alcohol use can sometimes cause withdrawal symptoms, so working with a healthcare provider to stop safely is important. Many OB-GYN offices screen for alcohol use during early prenatal visits specifically so they can connect patients with support. Being honest during those conversations leads to better care for both you and your baby.
For women who are not planning a pregnancy but could become pregnant, the safest strategy is straightforward: if you’re not using reliable contraception, treat alcohol the same way you would if you knew you were pregnant. Half of all pregnancies in the United States are unplanned, which means the window between conception and a positive test is one of the most common periods of accidental exposure. Closing that gap is one of the most effective things you can do.