About 1 in 33 babies in the United States is born with a birth defect, but many of those cases are linked to factors you can actively manage. While not every birth defect is preventable (some are genetic or have no known cause), the steps with the strongest evidence involve nutrition, avoiding harmful substances, managing chronic conditions, and staying on top of prenatal care.
Start Folic Acid Before You Conceive
Folic acid is the single most impactful supplement for preventing neural tube defects, which are serious problems with the brain and spine that develop in the first few weeks of pregnancy, often before you even know you’re pregnant. The U.S. Public Health Service recommends 400 micrograms (mcg) daily for anyone who could become pregnant.
If you’ve had a previous pregnancy affected by a neural tube defect, the recommendation jumps to 4,000 mcg daily, starting at least one month before conception and continuing through the first three months of pregnancy. Most prenatal vitamins contain 400 to 800 mcg. Fortified cereals, leafy greens, beans, and citrus fruits also contribute, but a supplement is the most reliable way to hit the target consistently.
Manage Blood Sugar and Chronic Conditions Early
If you have diabetes before pregnancy (type 1 or type 2), getting your blood sugar under tight control is critical. High blood sugar during the first 10 weeks of pregnancy can interfere with how a baby’s major organs form, particularly the heart and brain. That window is so early that by the time many people confirm a pregnancy, the highest-risk period is already underway.
This means the work starts before conception. If you’re planning a pregnancy and have diabetes, working with your care team to optimize blood sugar ahead of time gives your baby the best protection during those earliest weeks of organ development. Other chronic conditions like epilepsy, high blood pressure, and thyroid disorders also benefit from a preconception checkup to make sure your treatment plan is pregnancy-safe.
Avoid Alcohol, Tobacco, and Cannabis
There is no known safe amount of alcohol during pregnancy. Alcohol interferes with normal fetal growth and can cause birth defects. The most severe outcome, fetal alcohol syndrome, can lead to growth problems, intellectual disability, behavioral issues, and abnormal facial features. It is most likely in babies whose mothers drink heavily throughout pregnancy, but even moderate drinking carries risk.
Nicotine damages a developing baby’s brain and lungs and narrows blood vessels, meaning less oxygen and fewer nutrients reach the fetus. Smoking during pregnancy is linked to birth defects like cleft lip, as well as long-term problems including childhood asthma and obesity. E-cigarettes and vaping products still deliver nicotine and are not a safe alternative.
Cannabis products, including CBD and THC in any form, can affect fetal brain development and increase the risk of low birth weight, premature birth, and potentially stillbirth. Despite marketing claims, cannabis products promoted for morning sickness, anxiety, or pain relief during pregnancy are not FDA-approved and carry unproven safety claims.
Review Your Medications
Some prescription and over-the-counter medications can cause birth defects, especially during the first trimester when organs are forming. Common categories that raise concern include certain acne medications, some anti-seizure drugs, specific blood pressure medications, and a few types of antibiotics. Do not stop any prescribed medication on your own, but have a conversation with your prescriber as early as possible, ideally before conception, so that safer alternatives can be arranged if needed.
This applies to herbal supplements and high-dose vitamins too. “Natural” does not mean pregnancy-safe. A preconception medication review is one of the simplest and most effective things you can do.
Eat Safely to Prevent Infections
Certain foodborne infections pose a direct threat to fetal development. Listeria, a bacteria that can cause miscarriage and serious birth defects, is the biggest concern. The foods to be most careful with:
- Deli meats, hot dogs, and cold cuts: Heat to 165°F or until steaming hot before eating. Unheated deli meats are a common listeria source.
- Soft cheeses: Avoid queso fresco, brie, camembert, and blue-veined cheeses unless you can confirm they’re made from pasteurized milk.
- Raw or undercooked meat: Cook poultry and ground chicken or turkey to 165°F, ground beef and pork to 160°F, and whole cuts of beef, lamb, and pork to 145°F with a three-minute rest.
- Premade deli salads: Store-made potato salad, chicken salad, egg salad, and coleslaw carry higher risk. Homemade versions are safer.
- Unpasteurized juice, cider, and raw milk: Stick to pasteurized versions.
- Raw sprouts: Alfalfa and bean sprouts should be cooked until steaming hot.
- Unwashed produce: Wash all fresh fruits and vegetables thoroughly. Washed and then cooked is safest.
Cut melon left at room temperature for more than two hours (one hour above 90°F) should be discarded.
Protect Yourself From Toxoplasmosis
Toxoplasmosis is a parasitic infection found in raw meat, contaminated soil, and cat feces. It can cause serious birth defects if contracted during pregnancy. The practical steps are straightforward:
If you have a cat, have someone else handle litter box duty. If that’s not possible, wear disposable gloves and wash your hands thoroughly afterward. Change the litter daily, because the parasite doesn’t become infectious until one to five days after a cat sheds it. Feed cats commercial food only, never raw meat. Keep indoor cats indoors, avoid strays, and don’t adopt a new cat during pregnancy.
Wear gloves while gardening or handling sandbox sand, since outdoor cats use both as litter areas. Cover sandboxes when not in use. And because the parasite also lives in undercooked meat, the same cooking temperatures that protect you from listeria protect you from toxoplasmosis too.
Watch for Environmental Hazards
Lead and mercury are the two environmental toxins with the strongest links to developmental harm. Lead exposure can come from old paint in homes built before 1978 and from certain imported ceramic dishes that contain lead in their glaze. If you live in an older home and are planning renovations, have the paint tested before any sanding or scraping begins.
Mercury accumulates in certain large, long-lived fish. During pregnancy, limit or avoid shark, swordfish, king mackerel, and tilefish. Lower-mercury options like salmon, sardines, and shrimp provide beneficial omega-3 fatty acids without the same exposure risk. Two to three servings per week of these lower-mercury fish is generally considered safe and beneficial.
Stay Current on Vaccines
Some infections that cause birth defects are preventable through vaccination, but the timing matters. Rubella (German measles) is one of the most well-known causes of congenital birth defects, and it’s prevented by the MMR vaccine. However, MMR is a live vaccine and should not be given during pregnancy. If you’re planning to conceive, confirm your rubella immunity through a blood test and get vaccinated at least one month before becoming pregnant if needed.
During pregnancy, recommended vaccines include whooping cough (given between weeks 27 and 36 of each pregnancy), the seasonal flu vaccine, and the COVID-19 vaccine. RSV vaccine is an option during weeks 32 through 36 for pregnancies falling within September through January. These vaccines protect both you and the baby from infections that can cause complications. If you’re planning international travel while pregnant, discuss any additional vaccines four to six weeks before your trip.
Use Prenatal Screening to Your Advantage
Prenatal screening won’t prevent birth defects, but early detection gives you time to prepare, seek specialist care, or plan for interventions that improve outcomes. First-trimester screening, which combines a blood test and an ultrasound, is typically done between 10 and 13 weeks. It checks for conditions like Down syndrome and certain heart defects.
A second blood test, called the quad screen, is available between 15 and 22 weeks. It screens for Down syndrome, Edwards syndrome, and neural tube defects. Cell-free DNA testing (sometimes called NIPT) can be done as early as 10 weeks and screens for chromosomal conditions with higher accuracy than traditional blood tests, though it’s a screening tool, not a diagnosis. An anatomy ultrasound around 18 to 22 weeks provides a detailed look at the baby’s developing organs and structures.
None of these tests are mandatory, and a positive screen doesn’t always mean a problem exists. But they give you information early enough to make decisions and connect with the right specialists if something is detected.