Early pregnancy is when your baby’s major organs, brain, and spinal cord are forming, which makes the first trimester the most sensitive window for avoiding harmful exposures. The list of things to skip or limit covers food, drinks, medications, skincare products, and a few everyday habits you might not think twice about outside of pregnancy.
Fish With High Mercury Levels
Fish is a valuable source of protein and omega-3 fats during pregnancy, but certain species accumulate enough mercury to harm a developing nervous system. The FDA lists seven types of fish to avoid entirely: shark, swordfish, king mackerel, marlin, orange roughy, bigeye tuna, and tilefish from the Gulf of Mexico. These carry the highest mercury concentrations of any commonly sold seafood.
You don’t need to cut fish out altogether. The FDA recommends eating 8 to 12 ounces per week (two to three servings) of lower-mercury options like salmon, shrimp, tilapia, cod, and sardines. A single serving is about 4 ounces, roughly the size of your palm.
Foods That Carry Listeria Risk
Listeria is a type of bacteria that can cross the placenta and cause miscarriage, stillbirth, or serious infection in a newborn. Pregnant women are roughly 10 times more likely than the general population to get sick from it, and the foods it hides in aren’t always obvious.
The FDA specifically flags these items:
- Deli meats, hot dogs, and luncheon meats unless reheated until steaming hot
- Soft cheeses made with unpasteurized (raw) milk, including queso fresco, queso blanco, and requesón (these carry risk even when made with pasteurized milk)
- Unpasteurized milk and any foods made from it
- Refrigerated pâtés and meat spreads
- Refrigerated smoked seafood (like lox or smoked trout) unless it’s cooked into a dish like a casserole
The common thread is refrigerated, ready-to-eat foods that don’t get a final cooking step before you eat them. Heating these items to a steaming internal temperature kills Listeria.
Raw and Undercooked Foods
Raw sprouts, including alfalfa, clover, mung bean, and radish, are a well-documented source of Salmonella and E. coli. The warm, humid conditions needed to grow sprouts are ideal for bacteria, and rinsing alone won’t eliminate them. Cooking sprouts thoroughly does.
The same logic applies to raw or undercooked eggs, rare meat, and raw shellfish. These foods can carry bacteria or parasites that are more dangerous during pregnancy because your immune system is naturally dialed down to support the pregnancy.
Caffeine Over 200 Milligrams a Day
You don’t have to give up coffee entirely. The American College of Obstetricians and Gynecologists sets the limit at less than 200 milligrams per day, noting that moderate intake at that level does not appear to be a significant factor in miscarriage or preterm birth. For reference, a standard 12-ounce cup of brewed coffee contains roughly 100 to 140 milligrams, so one cup a day is generally within range. Keep in mind that tea, soft drinks, chocolate, and some medications also contain caffeine, so the total adds up faster than you might expect.
Alcohol and Tobacco
No amount of alcohol has been established as safe during pregnancy. Alcohol crosses the placenta freely, and during the first trimester, when organs and facial structures are forming, it can cause the range of physical and cognitive problems known as fetal alcohol spectrum disorders. The same applies to tobacco in all forms. Smoking restricts blood flow to the placenta, raising the risk of miscarriage, low birth weight, and preterm delivery. Vaping and nicotine replacement products also deliver nicotine, which affects fetal brain development.
Certain Herbal Teas
Herbal teas sound harmless, but several common varieties have raised safety concerns in pregnancy. Chamomile tea has been associated with a higher incidence of preterm labor or miscarriage with regular use. Peppermint tea in excess is contraindicated in early pregnancy because it can stimulate menstrual flow. Red raspberry leaf tea is often marketed for labor preparation, but it falls in a “use with caution” category and is not recommended in the first trimester. Ginger tea, sometimes used for nausea, should be limited to small amounts. The broader concern with all herbal teas is that they aren’t regulated the same way as food or medicine, so potency and contaminants can vary widely between brands.
Medications to Be Careful With
The first trimester is the highest-risk window for medication-related birth defects because organ formation is happening rapidly. Several categories deserve special attention.
Over-the-counter pain relievers like ibuprofen and naproxen (NSAIDs) are generally discouraged during pregnancy. Acetaminophen (Tylenol) is typically considered the safer alternative for pain and fever, though you should still use the lowest effective dose.
Retinoids, which are vitamin A derivatives found in prescription acne medications, are among the most well-established causes of birth defects. They can cause serious abnormalities in the face, heart, and brain. This is why dermatologists require pregnancy testing before prescribing them. Even high-dose vitamin A supplements carry risk: preformed vitamin A (retinol) above 10,000 IU per day during pregnancy is considered a risk factor for heart defects in the developing baby. UK guidelines take a more conservative approach, recommending that pregnant women avoid supplements with more than 5,000 IU.
Prescription medications including certain anti-seizure drugs, blood thinners like warfarin (especially dangerous between weeks 6 and 9), and specific antibiotics are known to cause birth defects. If you’re on any ongoing prescription, the important step is to talk with your prescriber before stopping or switching, since abruptly discontinuing some medications carries its own risks.
Skincare Ingredients to Skip
Most topical skincare products act locally on the skin and don’t reach the bloodstream in meaningful amounts. The two notable exceptions are retinoids and hydroquinone. Topical retinoids (tretinoin, adapalene, tazarotene) are in the same family as the oral retinoids linked to birth defects, and case reports have raised enough concern to warrant avoiding them. Hydroquinone, a skin-lightening agent used for dark spots and melasma, has a systemic absorption rate of 35% to 45% after topical application, which is substantially higher than other skincare ingredients. While the limited data available hasn’t shown increased birth defects, that high absorption rate makes it worth avoiding until more safety data exists.
Other common skincare ingredients like glycolic acid, benzoyl peroxide, and topical antibiotics used for acne are generally considered low risk based on their minimal absorption.
Hot Tubs and Saunas
Raising your core body temperature above 38.9°C (about 102°F) during the first trimester has been linked to neural tube defects. Research on hot tub use found that in a tub set to 41°C (106°F), it took at least 10 minutes for a woman’s core temperature to reach that threshold, and in a cooler 39°C (102°F) tub, it took at least 15 minutes. So brief dips may not be dangerous, but prolonged soaking can push your body temperature into a risky range. The safest approach in the first trimester is to keep hot tub sessions short (under 10 minutes) or skip them entirely. Saunas appear somewhat safer since none of the women studied were able to stay long enough for their temperature to reach dangerous levels, but the principle is the same: limit heat exposure.
Cat Litter and Toxoplasmosis
Toxoplasmosis is a parasitic infection commonly transmitted through contact with infected cat feces in a litter box, or through contaminated soil or water. A first infection during pregnancy can cause serious problems for the baby, including brain and eye damage.
If you have cats, the CDC recommends having someone else handle litter box duty. If that’s not possible, wear disposable gloves and wash your hands thoroughly afterward. Changing the litter daily is key because the parasite doesn’t become infectious until one to five days after a cat sheds it. The same caution applies to gardening: wear gloves when handling soil, since outdoor cats may have used garden beds as a litter box.
Excess Vitamin A in Supplements
Prenatal vitamins are formulated with pregnancy-safe amounts of vitamin A, usually in the form of beta-carotene rather than preformed retinol. The risk comes from stacking additional supplements or eating very large amounts of vitamin A-rich foods like liver on top of a prenatal vitamin. Preformed vitamin A above 10,000 IU per day is associated with a 1% to 2% absolute risk of heart malformations in the baby. Check your supplement labels for the form and amount of vitamin A listed, and avoid taking multiple supplements that each contain it.