Seafood

While fish are a great source of protein and heart-healthy omega-3 fatty acids, some are also chock full of mercury, a metal that can harm the developing brain of a fetus. Swordfish, tilefish, king mackerel and shark are particularly high in mercury and should be avoided during pregnancy, according to the U.S. Department of Health and Human Services. Pass on sashimi and other uncooked seafood, including raw oysters, too, health officials say. In addition to putting you and your baby at risk of mercury exposure, they may contain parasites such as tapeworm, which can rob your baby of vital nutrients.

Pregnant women can safely eat small amounts - up to one 6-ounce serving per week - of canned albacore or chunk white tuna, tuna steaks, halibut, snapper. You can consume up to two servings, or 12 ounces, of the safest fish, including salmon, canned light tuna, mahi mahi, pollock, catfish, cod and cooked shrimp, crab, clams, oysters and scallops, according to federal health authorities. For more information, the National Women's Health Information Center, a service of the U.S. Department of Health and Human Services, has a handy guide that details which fish are safe and which should be avoided during pregnancy.

Pets

Looking for an excuse to get someone else to clean the cat's litter box? Now you've got one. Health officials say pregnant women should avoid this nasty chore, which could put them at risk for an infection called toxoplasmosis. The disease is caused by a parasite that multiplies in the intestines of cats and is shed in cat feces. If a pregnant woman is exposed and becomes infected, she could pass it to her unborn child. Babies born infected can develop blindness or brain damage. The U.S. Centers for Disease Control has a good information sheet on toxoplasmosis on the agency's Web site.

Similarly, you should avoid all contact with rodents, including pet hamsters and guinea pigs and their urine, droppings and nesting materials. Rodents sometimes carry lymphocytic choriomeningitis virus (LCMV). If a pregnant woman is infected with LCMV, it can pass to the fetus and cause severe birth defects or miscarriage. If you do have a pet rodent, keep it in a separate part of the home and have other household members take care of it and clean its cage. For more information see the U.S. Centers for Disease Control and Prevention's Web page on LCMV.

Chemicals

Many herbicides, pesticides, and some cleaning solutions contain chemicals that may be harmful to your baby. It's best to avoid these kinds of products. If you must use them, protect yourself with a mask and gloves and make sure the room you're working in is well-ventilated.

Off gasses from paint can also be harmful, says Joel Evans, director of the Center for Women's Health in Darien, Conn. and author of The Whole Pregnancy Handbook: An Obstetrician's Guide to Integrating Conventional and Alternative Medicine Before, During and After Pregnancy. "People always want to paint the baby's room," he says. "This is not the time to paint. Paint and new carpeting produce off-gases," he explains, chemical vapors that may be harmful to a developing fetus and even to a young baby after it's born.

Hot tubs, saunas and steam rooms

Though your aching body may crave a hot bath, steam room or sauna, stay away from the heat. High temperatures can harm your fetus or cause you to faint.

Scented hygiene products

Avoid douches and perfumed feminine hygiene products, including scented sprays, sanitary napkins and bubble bath. These products can irritate the vagina and increase your risk of a urinary tract infection or yeast infection.

X-rays
X-rays are a form of radiation and should be avoided if possible during pregnancy. If you must have dental work or diagnostic tests, tell your dentist or physician that you are pregnant.

Some herbal remedies

Many nutritional supplements and herbs have proven to be safe and effective for use during pregnancy. For example, ginger root and vitamin B6 have been found useful in treating "morning sickness," the nausea associated with early pregnancy.

However, some herbs can cause miscarriage, premature birth, uterine contractions, or injury to the fetus. Among the oral supplements to avoid are: Arbor vitae, Beth root, Black cohosh, Blue cohosh, Cascara, Chaste tree berry, Chinese angelica (Dong Quai), Cinchona, Cotton root bark, Ephedra, Feverfew, Ginseng, Golden seal, Juniper, Kava kava, Licorice, Meadow saffron, Passion Flower, Pay D'Arco, Pennyroyal, Poke root, Roman Chamomile, Rue, Sage, Saint John's wort, Senna, Tansy, White peony, Wormwood, Yarrow, Yellow dock and Yohimbe.

The U.S. Food and Drug Administration recommends pregnant women consult their midwife or physician before taking any herbal products. You should also work with a trained and experienced herbalist and be sure to tell the practitioner you are pregnant.

Image: New Mexico Department of Health