The first trimester is when your baby’s major organs, brain, and spinal cord are forming, which makes the first 12 weeks the most sensitive window for avoiding harmful exposures. Some things on the “avoid” list are well known, like alcohol and smoking. Others, like certain skincare ingredients and deli meat, catch people off guard. Here’s a practical breakdown of what to skip and why.
Foods That Carry Infection Risk
Foodborne infections that would be mild for most adults can cause serious complications during pregnancy. Listeria is the biggest concern because it can cross the placenta and cause miscarriage or stillbirth, and pregnant people are about 10 times more likely to get sick from it than the general population. The foods most likely to harbor listeria include:
- Deli meats, hot dogs, and luncheon meats unless reheated until steaming hot
- Soft cheeses made with unpasteurized milk, plus queso fresco, queso blanco, and requesón (even pasteurized versions of these)
- Refrigerated smoked seafood labeled as lox, nova-style, kippered, or smoked, unless cooked into a dish like a casserole
- Refrigerated pâtés or meat spreads
- Unpasteurized milk or any product made from it
Raw sprouts, including alfalfa, clover, radish, and mung bean, are another high-risk food. Bacteria can enter the seed through tiny cracks in the shell before the sprout even grows, and once inside, they multiply rapidly during sprouting. Washing doesn’t remove them. Cooking sprouts thoroughly is the only way to make them safe.
The standard advice also applies: skip raw or undercooked eggs, raw cookie dough, rare meat, and raw shellfish. Use a food thermometer to make sure meat reaches a safe internal temperature.
High-Mercury Fish
Fish is actually encouraged during pregnancy for its omega-3 fatty acids, but certain species accumulate dangerous levels of mercury that can harm your baby’s developing nervous system. The FDA lists seven types to avoid entirely:
- King mackerel
- Marlin
- Orange roughy
- Shark
- Swordfish
- Tilefish from the Gulf of Mexico
- Bigeye tuna
You can safely eat two to three servings per week (one serving is 4 ounces) from the lower-mercury list, which includes salmon, shrimp, cod, tilapia, catfish, sardines, canned light tuna, pollock, and many others. If you eat from the “good choices” category, which includes albacore tuna and yellowfin tuna, stick to one serving per week.
Alcohol and Caffeine
No amount of alcohol has been shown to be safe at any point in pregnancy. The first trimester is particularly high-risk because alcohol interferes with the rapid cell division happening as organs form. There is no safe type, no safe amount, and no safe trimester.
Caffeine is a different story. The American College of Obstetricians and Gynecologists says moderate caffeine intake, under 200 mg per day, does not appear to be a major factor in miscarriage or preterm birth. That’s roughly one 12-ounce cup of coffee. Keep in mind that caffeine also shows up in tea, chocolate, soft drinks, and energy drinks, so you’ll want to count all sources together.
Medications and Supplements to Watch
Over-the-counter painkillers like ibuprofen and naproxen (NSAIDs) are not considered safe in the first trimester. Some studies have linked their use to an increased chance of miscarriage, especially when taken around conception or for extended periods. A small increased risk of heart defects and a rare abdominal wall defect called gastroschisis has also been reported. Acetaminophen (Tylenol) is generally considered the safer alternative for pain relief during pregnancy, though you should still use the lowest effective dose.
Excess vitamin A is another concern that surprises many people. The preformed type of vitamin A (retinol), found in liver, liver products like pâté, and fish liver oil supplements, can cause birth defects at high doses. The European Food Safety Authority sets the upper limit at 3,000 micrograms per day for women of childbearing age based on the risk to fetal development, but the UK goes further and recommends pregnant women avoid liver and liver products altogether. Your prenatal vitamin likely contains vitamin A in the form of beta-carotene, which is safe. Check labels and avoid stacking additional vitamin A supplements on top of your prenatal.
If you take any prescription medications, don’t stop them without talking to your provider, but do flag the pregnancy as early as possible so your medication plan can be reviewed.
Skincare Ingredients
Retinoids in skincare, including retinol, tretinoin, adapalene, and tazarotene, should be stopped during the first trimester. This precaution exists because oral retinoids like isotretinoin are known to cause severe birth defects, and topical versions are in the same chemical family. A large Nordic study of over 2,000 exposed pregnancies found no measurable increase in birth defects from topical retinoid use, which is reassuring if you used a retinol product before realizing you were pregnant. Still, the current recommendation is to avoid them throughout pregnancy.
High-concentration salicylic acid (the kind found in chemical peels) is also best avoided, though the low concentrations in most over-the-counter face washes are generally considered acceptable. Safe alternatives for acne during pregnancy include azelaic acid and topical clindamycin.
Hot Tubs, Saunas, and Overheating
Raising your core body temperature above 101°F (38.3°C) during the first trimester has been associated with neural tube defects. Hot tubs, saunas, steam rooms, and hot yoga all pose this risk. Cleveland Clinic advises avoiding all of these during pregnancy. If you want to take a bath, keep the water at or below 99°F (37°C), which feels warm but won’t raise your internal temperature.
This doesn’t mean you need to avoid exercise. In fact, moderate exercise is encouraged. The key is managing exertion so you don’t overheat. A good rule of thumb is the “talk test”: if you can carry on a conversation while exercising, you’re at an appropriate intensity. Aim for 20 to 30 minutes of moderate activity on most days.
Cat Litter and Soil
Toxoplasmosis is caused by a parasite commonly found in cat feces, raw meat, soil, and unwashed produce. A first-trimester infection can lead to serious problems for the baby. Cats pick up the parasite by hunting small animals or eating raw meat, then shed it in their stool.
If you have a cat, have someone else handle litter box duties. 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 it’s shed. Keep your cat indoors and feed only commercial cat food (never raw meat). Wear gloves while gardening too, since outdoor cats use garden beds and sandboxes as litter boxes. Don’t adopt a new cat while pregnant, and avoid handling strays.
Chemical Fumes and Solvents
Organic solvents and chlorinated solvents have been linked to miscarriage, birth defects, low birth weight, and preterm birth. Common ones include toluene (found in some paints and adhesives), xylene, benzene, and perchloroethylene (used in dry cleaning). You’re most likely to encounter these during home renovation projects, furniture refinishing, or in certain workplaces.
For everyday cleaning, work in a well-ventilated area and wear gloves. Avoid spray-on oven cleaners and products with strong solvent odors. If you’re painting a nursery, choose low-VOC or zero-VOC paint and let someone else handle the job if possible. The first trimester is the wrong time for major renovation projects that involve stripping paint, staining floors, or using industrial adhesives.
Contact Sports and High-Impact Activities
Activities with a risk of falling or abdominal impact, like skiing, horseback riding, contact sports, and cycling on rough terrain, are best put on hold. While your uterus is still protected by your pelvis in the first trimester, a hard fall or blow can still cause problems. Scuba diving is also off limits throughout pregnancy because the pressure changes can affect your baby’s developing circulatory system.
Safe alternatives include walking, swimming, stationary cycling, prenatal yoga, and low-impact strength training. A randomized trial of 300 women found that cycling exercise started in the first trimester and continued three times per week significantly reduced the risk of gestational diabetes and excessive weight gain.