What's Safe During Pregnancy? A Guide by Trimester

That diet soda, glass of wine at happy hour, or sushi lunch can wreak havoc on the mind of a mom-to-be as she remembers her first few weeks of pregnancy. But what is actually risky and what isn't?

We've asked two fetal and newborn health experts, Craig V. Towers, M.D., and Urania Magriples, M.D. to share which habits, activities, and beverages are safe and which aren't safe during every stage of pregnancy.

After conception, it takes about a week for a fetus to attach to the uterine wall, after which it starts drawing nutrients and oxygen from you. From this point on, what you put in your body starts to count, especially through the first three months while the fetus is forming.

A safe level of how much you can drink has yet to been determined by the experts, so most recommend abstaining all together. Heavy use during pregnancy can cause fetal alcohol syndrome, but that single glass of wine you had before you knew of your pregnancy won't.

However, it has been proven that smoking and pregnancy don't mix, so steer clear of smoking of any kind to prevent lower birth weight and other complications. 

• RELATED: Alcohol and Pregnancy: What You Need to Know

When used in moderation, coffee and other caffeinated food and beverages including soda, tea, and chocolate are probably not a problem.

Consuming more than 300 to 400 milligrams (or three to four eight ounce cups of coffee) per day can increase your risk of miscarriage, Magriples said.

Moderate amounts of diet soda have not been proven to be harmful, but they should be avoided. They'll add to your daily caffeine consumption and are empty calories, both for you and your baby.

• RELATED: How Much Caffeine Can You Safely Drink During Pregnancy?

Antihistamines like Benadryl used for allergies are safe for use during pregnancy, as are most cold remedies except decongestants, which can cause high blood pressure and uterine contractions.

It's best to carefully read labels before taking anything, however, and focus on treating only what you have symptoms of. Aspirin can impact blood clotting in the fetus, which is a concern during delivery. Instead, take Tylenol, Ibuprofen, or other over-the-counter medications in the non-steroidal anti-inflammatory family for pain relief. Taking limited qualities of these is okay, according to Towers. If used continuously, however, they can decrease the amount of amniotic fluid and affect your baby's kidneys.

If you take prescription medication regularly, you should talk to your doctor about how these drugs may affect your baby or pregnancy.

• RELATED: Which Medications Are Safe During Pregnancy?

Talk to your doctor about this one, but if you were in shape before you became pregnant, you should be able to carry on as usual without overheating or dehydrating yourself. If you waited until you became pregnant to exercise, start slowly with a walking, swimming, or aerobics program.

Lifting weights in moderation isn't a problem either, as long as you keep your shifting center of gravity in mind and be sure to lift from your legs, not your back.

• RELATED: Is It Safe to Exercise During Pregnancy?

Magriples and Towers recommend that you exercise strong caution when considering natural supplements. Herbs may be toxic in pregnancy and it's best to avoid them.

Taking vitamin A and E in high doses can also cause birth defects. High doses of vitamin A have been linked to brain, face, and heart defects while vitamin E in high does can pose a blood thinning risk in pregnant women. It's best not to exceed the recommended dietary allowance of either vitamin.

You should, however, be taking a prenatal vitamin.

• RELATED: The Best Prenatal Vitamin Options for Moms

It's nearly impossible to avoid radiation entirely during pregnancy, as it is occurs during X-rays, airplane travel, while using cell phones, or lying on the beach.

Fortunately, it takes a good deal of exposure to do any harm, Towers said. Concentrated high doses or repeated exposure to small amounts should be avoided if possible.

Rare and raw fish, shellfish, and meat should be avoided throughout your pregnancy.

Consuming any of these items exposes you to bacterial infection and parasites that can be passed on to your baby, which could result in impaired growth and brain development. This doesn't mean you have to avoid Japanese restaurants entirely, just order a fully cooked alternative to sushi.

As for fully cooked seafood, make smart choices.

• RELATED: What's Safe to Eat When You're Pregnant — And What's Not

Hair dye, which is absorbed through the scalp and enters the bloodstream, hasn't been proven to negatively affect your baby but should be avoided until your second trimester.

While they can be extremely relaxing, hot tubs cause profuse perspiration which brings more blood to your skin than the uterus. This could be dangerous to your baby, so take a short warm bath instead.

During your first trimester, there's a higher risk of miscarriage associated with traveling and during your third, you'll want to be close to home with your doctor or midwife. If you intend to travel, do so during your second trimester.

Make sure you stay hydrated and stress free as you travel, and walk around as much as possible to avoid blood clots when traveling by plane. Winter activities, including ice skating and skiing, can be fun on vacation but do pose a risk to you and your baby including premature labor and fetal injury if you fall after 20 weeks. Try cross-country skiing or snowshoeing instead.

• RELATED: Travel During Pregnancy: Your Nine-Month Guide