During pregnancy, your body shares everything with your developing baby, which means certain foods, medications, chemicals, and habits can directly affect fetal development. Some of these are well known (alcohol, smoking), while others are less obvious (deli meat, skincare products, certain pain relievers). Here’s a practical breakdown of what to steer clear of and why.
Fish High in Mercury
Fish is one of the best sources of protein and omega-3 fatty acids during pregnancy, so the goal isn’t to avoid seafood entirely. It’s to avoid the species that accumulate the most mercury, a metal that can damage a developing baby’s brain and nervous system.
Seven types of fish should be completely off the table: king mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish, and bigeye tuna. These sit at the top of the ocean food chain and concentrate mercury at the highest levels.
A second tier of fish is fine in smaller amounts, limited to one 4-ounce serving per week. This group includes halibut, mahi mahi, grouper, snapper, albacore (white) tuna, yellowfin tuna, Chilean sea bass, and bluefish. For everyday eating, the FDA recommends 2 to 3 servings per week (8 to 12 ounces total) from the lowest-mercury options: salmon, shrimp, tilapia, cod, catfish, sardines, canned light tuna, pollock, and trout, among many others.
Foods That Carry Listeria Risk
Listeria is a bacteria that can cross the placenta and cause miscarriage, stillbirth, or serious newborn infection. Pregnant women are roughly 10 times more likely than the general population to get listeriosis, which is why certain ready-to-eat foods need extra caution.
The main offenders:
- Deli meats, hot dogs, and luncheon meats unless reheated until steaming hot. Cold deli turkey on a sandwich is a common source of listeria exposure.
- Unpasteurized (raw) milk and any product made from it.
- Soft cheeses like queso fresco, queso blanco, and requesón, even when made from pasteurized milk. Other soft cheeses (brie, feta, goat cheese) are fine as long as the label says “pasteurized.”
- Raw sprouts of any kind, including alfalfa and bean sprouts, because bacteria can get inside the seed before it sprouts and can’t be washed off.
Alcohol
There is no known safe amount of alcohol during pregnancy, no safe trimester to drink it in, and no type of alcohol (wine, beer, liquor) that’s less risky than another. The CDC’s position is straightforward: all types, all amounts, all stages of pregnancy carry risk.
Alcohol in the bloodstream crosses the placenta freely. It’s associated with increased risk of miscarriage, preterm birth, stillbirth, and sudden infant death syndrome. It can also cause fetal alcohol spectrum disorders, a range of permanent intellectual, behavioral, and physical disabilities. The effects are dose-dependent, meaning more alcohol causes more harm, but there is no established threshold below which it’s considered safe.
Caffeine
The current guideline from the American College of Obstetricians and Gynecologists caps caffeine at 200 mg per day during pregnancy. That’s roughly one 12-ounce cup of coffee. Exceeding that amount has been linked to pregnancy loss and low birth weight, and the risk tends to increase with dose.
A 2023 integrative review raised questions about whether even 200 mg is conservative enough. Some studies found associations with low birth weight and pregnancy loss at levels below the recommended limit. For now, 200 mg remains the official ceiling, but keeping intake well under that number provides an extra margin of safety. Keep in mind that caffeine also shows up in tea, chocolate, soft drinks, and energy drinks, so it adds up.
Common Pain Relievers
Over-the-counter anti-inflammatory drugs like ibuprofen and naproxen pose real risks during pregnancy, particularly from 20 weeks onward. The FDA warns that these medications can reduce the baby’s kidney function, which in turn lowers amniotic fluid levels. Low amniotic fluid (oligohydramnios) can lead to problems with limb development and lung maturation. After 30 weeks, these drugs carry the additional risk of prematurely closing a blood vessel in the baby’s heart called the ductus arteriosus, which needs to stay open until birth.
The short version: avoid ibuprofen and similar anti-inflammatory drugs during pregnancy, especially in the second half. Acetaminophen (Tylenol) is generally considered the safer alternative for pain and fever, though you should still use the lowest effective dose. One exception to the anti-inflammatory rule: low-dose aspirin (81 mg) is sometimes specifically prescribed during pregnancy for conditions like preeclampsia prevention, and that use is considered appropriate under medical guidance.
Retinoid Skincare Products
Vitamin A derivatives used in anti-aging and acne treatments are among the most clearly harmful skincare ingredients during pregnancy. These include tretinoin (Retin-A), tazarotene, and isotretinoin (Accutane). In animal studies, topical retinoids caused spinal defects, skull abnormalities, heart malformations, and increased pregnancy loss. Oral isotretinoin is so strongly linked to birth defects that it’s absolutely contraindicated.
If you use any retinoid product on your skin, stop before trying to conceive or as soon as you learn you’re pregnant. For acne management during pregnancy, talk to your provider about alternatives. Many dermatologists consider certain concentrations of other topical treatments to be lower risk, but retinoids as a category should be avoided entirely.
Cat Litter and Garden Soil
Toxoplasma gondii is a parasite found in cat feces, and infection during pregnancy can cause serious problems for the baby including brain and eye damage. The parasite becomes infectious 1 to 5 days after a cat sheds it, which is why daily litter box changes reduce risk.
The ideal approach: have someone else handle litter box duties entirely. If that’s not possible, wear disposable gloves and wash your hands thoroughly with soap and warm water afterward. The same parasite can live in garden soil and sandboxes where cats may have defecated, so wear gloves while gardening and wash up when you’re done. Cover outdoor sandboxes when they’re not in use.
High Heat Exposure
Raising your core body temperature too high during pregnancy, particularly in the first trimester, is associated with neural tube defects like spina bifida and anencephaly. Hot tubs are the biggest practical concern because they maintain a constant high temperature that your body can’t cool down from the way it can during exercise.
Cleveland Clinic recommends keeping bath water at or below 99°F (37°C) to prevent your core temperature from rising. Standard hot tubs are set between 100°F and 104°F, which can raise your body temperature within 10 to 20 minutes. Saunas carry similar risks. If you do use a hot tub, limit your time to under 10 minutes and get out if you start to feel overheated or sweaty.
Certain Exercises and Contact Sports
Exercise during pregnancy is encouraged, not restricted. Walking, swimming, stationary cycling, and prenatal yoga are all beneficial. What you want to avoid are activities with a high risk of blunt trauma to the abdomen or hard falls: contact sports like soccer, basketball, and hockey, plus activities like horseback riding, downhill skiing, and gymnastics. ACOG also advises against overheating during intense training sessions.
After the first trimester, exercises that involve lying flat on your back for extended periods can compress a major blood vessel and reduce blood flow to the uterus. Switching to a side-lying or inclined position avoids this. Scuba diving is off limits throughout pregnancy because the pressure changes can create gas bubbles in the baby’s circulatory system.
Herbal Teas and Supplements
Herbal teas feel harmless, but some contain compounds that can stimulate the uterus or affect circulation. Chamomile is one of the most common examples. While a single cup is unlikely to cause problems, large quantities have been linked in some reports to higher rates of preterm labor and miscarriage, possibly because it can stimulate uterine contractions.
Raspberry leaf tea is often marketed as a way to prepare for labor, though no studies have confirmed it actually helps. It’s generally considered safe in the third trimester, but most providers suggest avoiding it earlier in pregnancy. Herbs that should be strictly avoided include pennyroyal, blue cohosh, and black cohosh, all of which have been associated with uterine stimulation or toxicity. As a general rule, if an herbal supplement or tea isn’t something you’d find on a grocery store shelf, check with your provider before using it. “Natural” doesn’t mean safe during pregnancy.