Nutrition for Pregnant Women, Trimester by Trimester

By Elizabeth M. Ward, M.S., R.D.

Yeah! You're pregnant. Now what? Here's how to eat, from conception to delivery, to ensure good nutrition during pregnancy.

First Trimester (Weeks 1 to 13)

Your pregnancy is probably not obvious to others yet, but you may be feeling the effects, including fatigue, lack of hunger, intense hunger, and a heightened sensitivity to smells that makes you sick to your stomach.

Your baby is very small and will weigh just about an ounce by the end of the 13 weeks. Yet, you're still eating for two, even though you don't require extra calories to support your pregnancy yet.

Your child's brain, heart, and other organs are developing, and it's important to stop drinking alcohol and taking illicit drugs, and to quit smoking. Ask your doctor about the safety of all prescription and over the counter medication you take during pregnancy.

Avoid fish that may have high mercury content, such as swordfish, king mackerel, tile fish and shark; mercury is harmful to baby's developing central nervous system. Stick with safer seafood, such as shrimp, canned light tuna, salmon, catfish, and pollock.

Pregnancy increases the need for folic acid, a B vitamin that helps prevent a class of birth defects called neural tube defects (NTD). The neural tube develops into the spinal cord. Make sure you consume 600 micrograms (mcg) of folic acid every day during pregnancy from fortified foods or dietary supplements.

A daily multivitamin or prenatal pill is likely to provide all the folic acid you need during pregnancy, and will also supply iron. You need 30 milligrams of iron daily when expecting to make the part of red blood cell that carries oxygen to your cells and to your baby's. Avoid taking dietary supplements with more than 3000 mcg of vitamin A. Excessive vitamin A may cause birth defects.

If you're vomiting or feeling queasy, try healthy mini-meals that include protein. Stay hydrated with fluids, fruits and vegetables. Generally speaking, so-called morning sickness ends by the second trimester, so hang in there!

According to the Centers for Disease Control, healthy pregnant women should get at least 150 minutes (2 hours and 30 minutes) per week of moderate-intensity aerobic activity, such as brisk walking, during and after their pregnancy. If you already do vigorous-intensity aerobic activity, such as running, you can continue doing so during and after your pregnancy as long as your pregnancy is without complications. If you don't exercise, regularly, it's possible to start now. Ask your doctor what is right for you.

Second Trimester (Weeks 14 through 26)

Babies begin to grow more rapidly during the second trimester, which is why women who started pregnancy at a healthy weight need about 330 calories more every day than before pregnancy. Ask your doctor about pregnancy weight gain.

Your appetite will probably be bigger, as your body adjusts to being pregnant, and morning sickness and fatigue begin to decline. Plan meals and snacks, so you get the best nutrition based on the number of calories. Make sure your daily eating plan is packed with protein, fiber, and healthy fats. Continue taking a multivitamin or prenatal supplement.

Drink about 10 cups of fluid daily. Water, milk, juice and even coffee and tea count toward your fluid intake. However, limit caffeine to 200 milligrams a day, about the amount found in 12 ounces of strong coffee or 4 cans of diet soda.

Exercise during pregnancy helps to keep weight gain within a healthy range. Don't overdo it, however. Pregnancy hormones make you more prone to injury, so you may need to change your routine. Try swimming, walking, and exercise classes designed for pregnant women. Avoid activities that may cause you to fall, including skiing, horseback riding, and biking outside, and those with pressure changes, such as scuba diving.

The Third Trimester (Weeks 27 through 40)

You're in the home stretch! Your baby is growing by leaps and bounds now. His brain, lungs and other organs continue to mature to handle life outside the womb, and he is accumulating calcium in his bones, and iron in this red blood cells.

Your baby's growth is why you need 120 calories more daily than during the second trimester. As you get closer to delivery, it may be difficult to eat 450 extra calories every day because the baby is crowding your digestive tract, resulting in heartburn and constipation.

To relieve heartburn, break down your daily food intake into smaller, more frequent meals. For example, eat half your breakfast, and have the rest two hours later. To prevent constipation, include high-fiber foods such as whole grains, fruits, and vegetables at meals and snacks and drink plenty of fluid. Keep taking your daily multivitamin supplement.

Keep moving! You're about 20 to 30 pounds heavier than you were when you conceived, so you may become tired more quickly. Break down exercise into 10- or 20-minute periods instead of 30 or 60 minutes. If just thinking about exercise makes you tired, tell your doctor. You may have an iron deficiency.

About the Author

Elizabeth M. Ward, M.S., R.D., is a registered dietitian, a writer, and mother of three. She has worked at the Joslin Diabetes Center and the American Heart Association, and for seven years counseled children and adults about healthy eating and disease prevention at Harvard Vanguard Medical Associates in Boston.

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