IN THIS CHAPTER
Understanding healthy weight gain — yours and your baby’s
Optimizing your diet
Taking food safety into account
Accounting for special diet needs
Staying fit during pregnancy
Through the ages, women have received all kinds of advice about what, and how much, to eat while they’re expecting. Cultural traditions, religious beliefs, and scientific thinking have all had their influence. Your practitioner’s advice is likely to depend on your particular health habits and your size when your pregnancy begins. Also, if you’re carrying more than one baby, you’re expected to gain more than the average number of pounds.
Of course, health involves more than just eating well. Exercise is as important while you’re pregnant as it was before, although what and how much you do to stay fit may change as your pregnancy progresses. This chapter provides you with basic information about proper nourishment and exercise during pregnancy. For more in-depth information, head to Books 3 and 4, which are devoted to nutrition and staying fit and active while pregnant.
Looking at Healthy Weight Gain
Starting pregnancy at a healthy weight and gaining weight at a moderate pace throughout pregnancy can help ensure that your baby grows and develops normally and that you stay healthy as well. So what is healthy? This section explains in more depth the weight issues associated with pregnancy.
Determining how much is enough
The best way to figure out your ideal weight — and weight gain — is to look at your body mass index (BMI), a number that takes into account both height and weight.
After you know your body mass index (many BMI calculators are available online), you can figure out your ideal weight gain during pregnancy by consulting Table 3-1. (But don’t forget, this number refers to women carrying only one baby!)
Table 3-1 Figuring Out Your Ideal Weight Gain
|
Body Mass Index |
Recommended Weight Gain |
|
Less than 19.8 (underweight) |
28 to 40 pounds (12.5 to 18 kilograms) |
|
19.9 to 26 (normal weight) |
25 to 35 pounds (11.5 to 16 kilograms) |
|
26 to 29 (overweight) |
15 to 25 pounds (7 to 11.5 kilograms) |
|
29 or more (obese) |
15 pounds (7 kilograms) or less |
These numbers refer to total weight gain during the entire pregnancy, so you won’t know whether you’ve hit the target until delivery day. Scientific research hasn’t determined the optimal pattern of weight gain throughout pregnancy. Gaining very little weight early on (when you may be in the throes of morning sickness) may have less effect on fetal growth than poor weight gain in the late second or third trimester. Some women gain weight inconsistently, putting on a large number of pounds early and then much less later on. Nothing is necessarily unhealthy about this pattern, either.
Avoiding weight obsession
Use the charts of optimal weight gain as a guide, but don’t become fanatical about how much you weigh. Even if the amount you gain is somewhat off course, if your doctor says that the baby is growing normally, you have nothing to worry about. Women who gain more than average can still have healthy babies, and so can women who gain very little.
If your weight gain is way too high or way too low, your doctor can check the baby’s growth by measuring the fundal height (refer to Book 1, Chapter 2) or schedule you for a sonogram. If you deviate significantly from the recommended weight gain, your doctor will probably want to evaluate your diet. He may refer you to a nutritionist or dietitian who can give you specific advice about what and how much to eat.
WHERE DOES THE WEIGHT GO?
The good news is that the weight you gain during pregnancy doesn’t all go to your thighs. Then again, it doesn’t all go to the baby, either. A pregnant woman typically adds a little to her own body fat. It’s a myth, however, that you can tell whether she’s going to have a boy or a girl based on her pattern of weight gain (more in the hips or more in the belly). Here’s a realistic view of your weight gain — assuming it’s 27 pounds, which is fairly average:
|
Baby |
7 pounds (3,180 grams) |
|
Placenta |
1 pound (455 grams) |
|
Amniotic fluid |
2 pounds (910 grams) |
|
Uterus |
2 pounds (910 grams) |
|
Breasts |
1 pound (455 grams) |
|
Fat stores |
7 pounds (3,180 grams) |
|
Body water |
4 pounds (1,820 grams) |
|
Extra blood |
3 pounds (1,360 grams) |
Understanding your baby’s weight gain
Your baby’s bulking-up pattern is likely to progress slowly at first and then pick up at about 32 weeks, only to slow again in the last weeks before birth. At 14 to 15 weeks, for example, the baby puts on weight at about 0.18 ounce (5 grams) per day. At 32 to 34 weeks, he puts on 1.06 to 1.23 ounces (30 to 35 grams) per day (that’s about half a pound or 0.23 kilograms each week). After 36 weeks, the fetal growth rate slows to about a quarter of a pound per week, and by 41 to 42 weeks (you’re overdue at this point), minimal or no further fetal growth may occur. In addition to your diet and weight gain, the following factors affect fetal growth:
· Cigarette smoking: Smoking can reduce the birth weight by about half a pound (about 230 grams).
· Diabetes: If the mother is diabetic, the baby can be too big or too small.
· Genetic or family history: In other words, basketball players usually don’t have children who grow up to be professional jockeys!
· Fetal infection: Some infections affect growth.
· Illicit drug use: Drug abuse can slow fetal growth.
· Mother’s medical history: Some medical problems, like hypertension or lupus, can affect fetal growth.
· Multiple pregnancy: Twins and triplets are often smaller than singles.
· Placental function: Placental blood flow that’s below par can slow down the baby’s growth.
Your practitioner keeps an eye on your baby’s growth rate, most often by measuring fundal height and paying attention to your weight gain. If you put on too little or too much weight, if your fundal height measurements are abnormal, or if something in your history puts you at risk for growth problems, your doctor is likely to send you for an ultrasound exam to more accurately assess the situation.
Taking Stock of What You’re Taking In
Sticking to a well-balanced, low-fat, high-fiber diet is important not only for your baby but also for your own health. Consuming adequate protein is also important because protein carries out many of the body’s functions. The fiber in your diet helps to prevent or reduce constipation and hemorrhoids. By not consuming too much fat, you help keep your heart healthy and avoid putting on extra pounds that may be difficult to shed.
If your diet is balanced and not too heavy in sugar or fat, you don’t need to modify the way you eat dramatically. During pregnancy, you should take in roughly 300 extra calories a day, on average. That means that if you’re at a healthy weight and you’re taking in 2,100 calories per day, while pregnant you should take in an average of 2,400 calories per day (perhaps a little less during your first trimester and a little more during your third trimester).
You should not increase your caloric intake by eating a hot fudge sundae every day. Filling these additional requirements with nutritious foods is key. Your practitioner will likely advise you to take some supplemental vitamins and minerals, too. Keep reading to find out which foods and supplements are best for you, and head to Book 3 for detailed guidance.
Using the USDA MyPlate
No single food can satisfy all your nutritional needs. The USDA MyPlate, shown in Figure 3-1, is a general guideline that illustrates the relative proportions of servings you should eat in each group. To get some specific recommendations tailored for your pre-pregnancy weight and activity level, go to www.choosemyplate.gov/moms-daily-food-plan and create a profile to receive a personalized daily food plan.
Source: U.S. Department of Agriculture
FIGURE 3-1: Use the USDA MyPlate guide to help you eat healthily during pregnancy.
MyPlate includes the following food groups:
· Grains: Although many types of grains are healthy to eat, MyPlate refers to fortified dry and cooked cereals. Choose ones that are fortified with folic acid when possible.
· Vegetables: Vegetables are divided into five groups, based on their nutrient content. Pregnant women should try to fill half of their plate with fruits or vegetables. The following list orders vegetables from highest nutrient content to lowest and includes examples within each category:
· Dark green vegetables (spinach, dark green leafy lettuce, romaine lettuce, broccoli, kale, turnip greens, watercress)
· Orange and red vegetables (carrots, pumpkin, sweet potatoes, certain types of squash, red peppers, and tomatoes)
· Dry beans/peas (pinto, black, garbanzo, kidney, navy, and white beans; split peas; lentils; soybeans and tofu)
· Starchy vegetables (potatoes, corn, green peas, green lima beans)
· Other vegetables (cabbage, cauliflower, iceberg lettuce, green beans, celery, green peppers, mushrooms, onions, asparagus, cucumbers, eggplant)
· Fruits: Not only are fruits a good source of vitamins and minerals, but they also provide fiber, which is important during pregnancy to help reduce constipation. You can choose fresh, frozen, canned, or dried fruits. Go easy on the fruit juices, though, because they can contain lots of sugar.
· Dairy: Foods that fall in this group include milk, yogurt, and cheese, and all are great sources of calcium. Focus on lowfat or fat-free milk products whenever possible. An average-sized woman needs to consume about 3 cups of milk or milk products per day.
· Protein: Meat, poultry, fish, and nuts fall into this category. Focus on lowfat and lean foods and vary your choices. Baking, broiling, and grilling are the healthiest ways to cook meat, poultry, and fish. During pregnancy, you should eat 5 to 7 ounces of food from this category daily.
What about oils (fats that remain liquid at room temperature) and fats that are solid at room temperature? Healthy fats — unsaturated fats that come from vegetables oils, nuts, seeds, and fish — are good for you, although fewer than 10 percent of your fat intake should come from saturated fats (typically those that remain solid at room temperature). Avoid trans fats (a type of saturated fats that are common in processed foods and have been associated with obesity and heart disease) altogether.
Also, as your pregnancy progresses, your body needs a lot of extra fluid. Early on, some women who don’t drink enough liquid feel weak or faint. Later in pregnancy, dehydration can lead to premature contractions. Make a point of drinking plenty of water (or milk) — about six to eight glasses a day, and a bit more if you’re carrying more than one baby.
Experiencing morning sickness during the first trimester is very common (see Book 2, Chapter 1). If you’re experiencing this nausea and can’t eat a well-balanced diet, you may wonder whether you’re getting enough nutrition for you and the baby. You actually can go for several weeks not eating an optimal diet without any ill effects on the baby. You may find that the only foods you can tolerate are foods heavy in starch or carbohydrates. If all you feel like eating are potatoes, bread, and pasta, go right ahead. Keeping something down is better than starving.
IS CAFFEINE SAFE DURING PREGNANCY?
No evidence suggests that caffeine causes birth defects. However, if you consume caffeine in large amounts, it may raise the risk of miscarriage. Most studies suggest that it takes more than 200 milligrams (mg) of caffeine a day to affect the fetus. The average cup of coffee (an 8-ounce cup of regular coffee — not the super-mega size or an espresso or cappuccino!) has between 100 and 150 mg of caffeine. Caffeinated tea has slightly less caffeine — about 50 to 100 mg — and soft drinks have approximately 36 mg per 12-ounce serving. So drinking one 8-ounce cup of coffee (or the equivalent caffeine content in other foods or beverages) per day is usually okay during pregnancy.
Supplementing your diet
If your diet is healthy and balanced, you get most of the vitamins and minerals you need naturally — with the exception of iron, folic acid, and calcium. To make sure you get enough of these nutrients and to guard against inadequate eating habits, your practitioner is likely to recommend prenatal vitamins. In the case of vitamins, more isn’t necessarily better; take only the prescribed number of pills each day.
Several different prenatal vitamins are available, and they’re generally equivalent. Some are better tolerated than others, so if you find the one you’re taking is not agreeable to you, try a different brand. Also, many now contain omega-3 fatty acid supplementation. Some data suggests that omega-3 supplements may decrease the risk of preterm delivery and may have a beneficial effect on the newborn brain, but this hasn’t been proven.
During the early months, if your vitamins make you nauseous, skipping them until you feel better is perfectly safe for the baby. If you’re very early in your pregnancy (4 to 7 weeks), you can take just a folic acid supplement, which is sometimes easier to tolerate, until you can handle the complete prenatal vitamin pill. If later on in the pregnancy you get a stomach virus and can’t tolerate vitamins for some time, that’s not a problem, either. The growing baby is able to get what he needs, even at the expense of the mom (a theme that continues throughout life!).
Iron
You need more iron when you’re expecting because both you and the baby are making new red blood cells every day. On average, you need 30 milligrams (mg) of extra iron every day of your pregnancy, which is what most prenatal vitamins contain. Blood counts can easily drop during pregnancy because your body gradually is making more and more blood plasma (fluid) and relatively fewer red blood cells (a condition that is called a dilutional anemia). If you do develop anemia, you may need to take an extra iron supplement.
Foods rich in iron include chicken, fish, red meat, green leafy vegetables, and enriched or whole-grain breads and cereals. You can raise the iron content of foods by cooking them in cast-iron pots and skillets.
Calcium and vitamin D
You need about 1,200 milligrams of calcium and 2,000 units of vitamin D every day while you’re pregnant. Most women actually get much less. If you’re already starting out somewhat deficient in calcium and vitamin D, the calcium requirements of the developing baby will only make matters worse for you. A fetus can extract enough calcium from his mother, even if that means getting it at the expense of the mother’s bones. So the extra calcium and vitamin D needed during pregnancy are really aimed at protecting you and your health. The vitamin D helps you store the calcium.
Prenatal vitamins contain only about 200 to 300 mg of calcium (about one-quarter of the U.S. Recommended Daily Allowance), so you need to get calcium from other sources — your diet or a calcium supplement — as well. Getting enough calcium from your diet alone is possible if you really pay attention. You can get it from three to four servings of calcium-rich foods, such as milk, yogurt, cheese, green leafy vegetables, and canned fish with bones (if your stomach can take it). Supermarkets also stock special lactose-free foods that are high in calcium.
Determining Which Foods Are Safe
Expectant moms often ask about nutrition, and they specifically want to know which foods they should avoid. This section identifies the potentially harmful foods and also debunks some common myths about other foods.
Eyeing potentially harmful foods
If you’re healthy, you can probably confidently eat most of the foods you usually eat. Nonetheless, the following list contains some potential dangers that we feel we ought to mention:
· Cheeses from unpasteurized or raw milk: These cheeses may contain certain bacteria, such as Listeria monocytogenes, Salmonella, and E. coli. Listeria, in particular, has been linked to certain pregnancy complications, such as premature labor or even miscarriage. The FDA mandates that all cheeses sold in the United States be either made from pasteurized milk or aged more than 60 days (which makes the likelihood of listeria extremely low), so most cheeses you buy at your local market are safe. Just check the label to be sure.
· Raw or very rare meat: Steak tartare or very rare beef or pork may contain bacteria, such as Listeria, or parasites, such as Toxoplasma. Adequate cooking kills both bacteria and parasites, so you want your food to be cooked medium-well to well-done.
· Liver: Liver contains extremely high amounts of vitamin A (more than ten times the amount recommended for a pregnant woman). Consuming more than 10,000 international units (IUs) of vitamin A daily (the recommended daily allowance for pregnant women is 2,500 IU) was linked to birth defects in one study. Scientists haven’t proven this danger unequivocally, but you may want to find a substitute for that liver-and-onions craving in the first trimester.
Debunking popular food myths
Many of the foods that have at one time or another been thought dangerous for pregnant women aren’t likely to harm you or your baby. Although you don’t have to avoid the following foods, they should be eaten in moderation, especially those that are manufactured (as opposed to natural) products:
· Cheeses: Not only do most people believe that processed and pasteurized cheeses are safe, but these cheeses are also a great source of both protein and calcium. The one caveat? Unpasteurized cheese. Head to the preceding section for details.
· Fish: Fish is a great source of protein and vitamins, and it’s also low in fat. In fact, the high levels of protein, omega-3 fatty acids, vitamin D, and other nutrients make fish an excellent food for pregnant mothers and their developing babies.
However, certain fish — shark, mackerel, swordfish, and tilefish — contain high levels of mercury. The FDA currently recommends you avoid fish with high levels of mercury when you’re pregnant. The USDA guidelines say you can still enjoy up to 12 ounces (two average meals) per week of fish and shellfish lower in mercury, like salmon, haddock, tilapia, cod, sole, and shrimp, or up to 6 ounces of albacore tuna per week. Avoid tuna steak, due to mercury levels, and raw seafood and oysters due to bacteria (Vibrio vulnificus and Vibrio parahaemolyticus) that can cause infections.
Don’t let your concern for mercury make you give up fish altogether, because two studies looking at fish consumption in pregnant women showed that women who eat fish may actually have lower rates of preterm delivery, and their children may have higher IQs.
· Sushi: Raw fish (except raw shellfish) actually carries a very small risk of a parasitic infection (about one infection in 2 million servings — less than the risk of getting sick from eating chicken!). Pregnancy doesn’t increase the danger, and your fetus is unlikely to suffer any harm from such an infection. Most important is to make sure that the fish comes from a reliable source and that it is stored properly.
· Smoked meats or fish: Many pregnant women worry about eating smoked meats and fish because they’ve heard that these foods are high in nitrites or nitrates. Although these foods do contain these substances, they won’t hurt your baby if eaten in moderation.
· Sweeteners: You should limit sweeteners (including sugar) in general, but they should be safe for your baby:
· Aspartame (Equal or NutraSweet): Aspartame (a common component of low-calorie foods and beverages) is a type of amino acid, and the body is accustomed to amino acids because they’re what all proteins are made of. No medical evidence shows that aspartame causes any problems for the growing baby.
· Sucralose (Splenda): Sucralose is a low-calorie sweetener, with less than 2 calories per teaspoon. It’s actually a type of sugar, but it’s much more potent than regular table sugar, so you only need small amounts to sweeten things up. Because it’s a type of sugar, it should have no harmful effects on your developing baby.
· Stevia leaf extract sweeteners (Truvia or Stevia): The most recent additions to nonsugar-based sweeteners are derived from the stevia leaf. Although the data is somewhat limited, they appear to be completely safe to use in pregnancy.
Considering Special Dietary Needs
You may find that you need to tailor the rules of healthy nutrition to fit your particular eating habits — for example, if you’re a vegetarian. This section addresses some of the issues that arise for women with special nutritional needs.
Eating right, vegetarian-style
If you’re a vegetarian, rest assured you can produce a healthy baby without eating steak. But you do have to plan your diet more carefully. Vegetables, whole grains, and legumes (peas and beans) are rich in protein, but most don’t have complete proteins. (They don’t contain all the essential amino acids that your body can’t produce by itself.) To get all the necessary protein, you can combine various proteins — for example, whole grains with legumes or nuts, rice with kidney beans, or even peanut butter with whole-grain bread. The combination doesn’t have to occur at the same meal, only on the same day, but a good rule of thumb is to try to get some protein with each meal.
If you don’t eat any animal products, including milk and cheese, your diet may not provide enough of six other important nutrients: vitamin B12, calcium, riboflavin, iron, zinc, and vitamin D. Bring up the topic with your doctor. You may also want to discuss your diet with a nutritionist. In addition, vegetarian and vegan vitamin supplements are available over the counter.
Staying healthy, vegan-style
Vegans, like vegetarians, do not consume meat, fish, or poultry, but they also eliminate all animal products from their diet. So, no milkshakes or eggs-over-easy for vegans! Because many vegans consume fewer calories and may start their pregnancy with a lower BMI, they need to pay extra attention to make sure they’re getting enough calories and nutrition for themselves and their growing baby. Here are some helpful hints if you are a pregnant vegan:
· Vitamin B12 deficiency is not unusual for vegans, so make sure you’re getting enough vitamin B12, and speak with your doctor about possible supplementation.
· Good sources of protein can be found in soy products, beans, whole grains, lentils, and tofu.
· Pay attention to calcium, because calcium and vitamin D are needed for you and your baby’s bones. Good sources of calcium for vegans include calcium-fortified soy milk and juice, calcium-set tofu, soybeans and soy nuts, green leafy vegetables (such as Chinese cabbage, kale, and mustard greens), and okra. Dry cereals are a source of Vitamin D.
· Iron is super important during pregnancy, because your body needs to increase its blood supply for the pregnancy. You can find iron in dried beans, green leafy vegetables, and tofu.
· Folate is another important factor that has been shown to reduce the chance of the baby developing a condition called a neural tube defect. It’s important to have enough folate onboard before the pregnancy starts and especially through the first trimester. Folate can be found in enriched breads, pasta, cereals, and orange juice.
· DHA (docosahexaenoic acid) is great for the developing fetal brain. Many people think of DHA as occurring only in fish, but a form of DHA can also be found in flaxseed, flaxseed oil, canola oil, walnuts, and soy nuts.
Working Out for Two
During pregnancy, exercise helps your body in many ways: It keeps your heart strong and your muscles in shape, and it relieves the basic discomforts of pregnancy — from morning sickness to constipation to achy legs and backs. The earlier in pregnancy a woman gets regular exercise, the more comfortable she is likely to feel throughout the 40 weeks. Regular exercise may even make for shorter labor.
So if you’re in good health and not at risk for obstetrical or medical complications, by all means go ahead and continue with your exercise program — unless your program calls for climbing Mount Fuji, entering a professional boxing match, or some other super-strenuous activity. Go over your exercise program with your practitioner so he knows what you’re doing and so you can ask any questions you have.
As good as exercise is for most pregnant women, we don’t advise it for everyone. If you have any of the following conditions (see Book 6 for details), you may be better off not working out — at least until you discuss the situation with your doctor:
· Bleeding
· Incompetent cervix
· Intrauterine growth restriction
· Low volume of amniotic fluid
· Placenta previa (late in pregnancy)
· Pregnancy-induced hypertension
· Premature labor or preterm rupture of the membranes
· Carrying triplets or more
Adapting to your body’s changes
Even if you work out in moderation, remember that pregnancy causes your body to undergo real physical changes that can affect your strength, stamina, and performance. The following list details some of those changes:
· Cardiovascular changes: When you’re pregnant, the amount of blood that your heart pumps through your body increases. That increase in blood volume usually has no effect on your workout. (Some women feel as though they hear their heartbeat in their ears because of the increased volume.) Also, if you lie flat on your back, especially after about 16 weeks of pregnancy, you may find yourself feeling dizzy or faint — or even nauseous. Known as supine hypotension syndrome, this dizziness sometimes happens when the enlarging uterus presses down on major blood vessels that return blood to the heart, thus decreasing the heart’s output. It happens even more readily if you’re having a multiple pregnancy and your uterus is that much heavier.
If you’re doing any exercises that require you to lie on your back (or if you’re accustomed to sleeping on your back), put a small pillow or foam wedge under the right side of your back or your right hip. The pillow tilts you slightly sideways and effectively lifts your uterus off the blood vessels.
· Respiratory changes: Your body is using more oxygen than usual to support the growing baby. At the same time, breathing is more work than it used to be because the enlarging uterus presses upward against the diaphragm. For some women, this difficulty makes performing aerobic exercise a little harder.
· Structural changes: As your body shape changes — bigger abdomen, larger breasts — your center of gravity shifts, which can affect your balance. You notice it especially if you dance, bicycle, ski, surf, ride horses, or do anything else (walk tightropes, maybe?) where balance is important. In addition, pregnancy hormones cause some laxness in your joints, which also can make balance more difficult and may increase your risk of injury.
· Metabolic changes: Pregnant women use carbohydrates faster than nonpregnant women do, which means that they’re at a higher risk of developing hypoglycemia (low blood sugar). Exercise can be very useful in helping lower and control blood sugar levels, but it also increases the body’s need for carbohydrates. So if you exercise, make sure you’re eating an adequate amount of starch just before you work out.
· Effects on the uterus: One study of women at term (far enough along to deliver) showed that their contractions increased after moderate aerobic exercise. Another study indicated that exercise is associated with a lower risk of early labor. But most studies have shown that exercise has no effect either way, and exercise does not pose a risk of preterm labor in healthy pregnant women.
· Effect on birth weight: Some studies have shown that women who work out strenuously (at high intensity) during pregnancy have lighter-weight babies. The same effect appears to occur in women who perform heavy physical work in a standing position while they’re pregnant. But this decrease in birth weight seems to be due mainly to a decrease in the newborn’s subcutaneous fat. In other words, more strenuous exercise has no effect on the fetus’s normal growth.
Exercising without overdoing it
Your changing body is going to demand a change in exercise routine. Don’t beat yourself up if you find that pregnancy makes it harder to continue the workouts you’re accustomed to. Modify your program according to what you can reasonably tolerate.
Listen to your body. If weight lifting suddenly hurts your back, lighten up. You may find it easier to perform non-weight-bearing exercises like swimming or stationary bicycling. No matter what your particular exercise regimen may be, keep in mind the basic rules for working out during pregnancy:
· If you have a moderate exercise routine, keep it up. If you’ve been pretty sedentary, don’t suddenly plunge into a strenuous program; ease in slowly to avoid putting too much strain on your body.
Keeping up a regular schedule of moderate activity is better than engaging in infrequent spurts of intense exercise, which are more likely to cause injury.
· Avoid overheating, especially during the first six weeks of pregnancy. On very hot or humid days, don’t exercise outdoors. Carry a bottle of water to every exercise session and stay well hydrated.
· Avoid exercising flat on your back for long periods of time; doing so may reduce blood flow to your heart.
· Avoid anything that puts you at risk of being hurt in the abdomen, like road/mountain biking. Steer clear of high-impact, bouncy exercises that can tax your loosening joints.
· Throughout the nine months, low- or moderate-impact workouts make more sense than high-impact ones.
· If you feel fatigued, dizzy, faint, or nauseous, by all means, stop.
· Eat a well-balanced diet that includes an adequate supply of carbohydrates (see “Taking Stock of What You’re Taking In,” earlier in this chapter).
· Talk to your practitioner about what your peak exercise heart rate should be. (Many practitioners suggest 140 beats per minute as the upper limit.) Then regularly measure your heart rate at the peak of your workout to make sure it’s at a safe level.
· 
Stop exercising and talk to your doctor if you experience any of these symptoms:
· Shortness of breath that is persistent or out of proportion to the exercise you’re doing
· Vaginal bleeding
· Rapid heartbeat (that is, more than 140 beats per minute)
· Dizziness or feeling faint
· Any significant pain
Comparing forms of exercise
Now isn’t the time to shoot for that Ms. Fitness title, but that certainly doesn’t mean you can’t exercise. Because your pregnant body demands you take new precautions, choose your style of exercise carefully.
Working your heart: Aerobic exercise
Weight-bearing exercises like running, walking, aerobics, and using a stair-climbing machine or an elliptical trainer are great, as long as you don’t do too much. These exercises require you to support all your weight, which is ever-increasing. Because your joints are loosening and your center of gravity is shifting at the same time, you run a slightly higher risk of injuring yourself. Remember to do only what you know you can rather than setting off on a new exercise routine that is too demanding for your current state of fitness, not to mention your pregnancy.
Pilates is a popular mind-body conditioning program focused on strengthening the core postural muscles important in maintaining your balance and supporting your spine. For the most part, continuing Pilates classes while you’re pregnant is safe, as long as you avoid lying flat on your back for long periods of time.
If you choose to take aerobics or Pilates classes, look for those designed specifically for pregnant women. If no classes are available, talk to the instructor to find modifications for exercises that are inappropriate.
You may find it easier, particularly later in pregnancy, to perform non-weight-bearing exercises. Because your weight is supported, you have less chance of injuring yourself, and your joints aren’t stressed. If you’re new to exercise, a low-intensity workout in the pool or on a stationary bike is ideal.
Downhill skiing, waterskiing, and horseback riding put you at risk of falling with significant impact, which could injure you or your baby. Although these activities may be fine early in pregnancy, talk to your doctor before doing them in your second or third trimester. Cross-country skiing is less risky, especially if you’re experienced.
Strengthening your muscles
You won’t get a great cardiac benefit from weight lifting, yoga, or body sculpting, but you can improve your muscle tone and flexibility, which comes in handy during labor and delivery.
Weight-lifting machines may be preferable to using free weights because you know you won’t drop the weights onto your abdomen. Also avoid using very heavy weights, which can cause injury to your joints and ligaments. If you use free weights, do so with caution — and preferably with the help of a trainer or a skilled friend. A trainer can also show you the proper way to exhale and inhale during lifting.
Breathing well while you lift weights is important because it lessens the chance that you might bear down (otherwise known as the valsava maneuver, a method of increasing abdominal pressure), which can reduce blood flow, raise your blood pressure, and stress your heart.
Yoga, which is a great choice for pregnant women, not only is an excellent form of exercise but may also be helpful in mastering breathing and relaxation techniques. Yoga is particularly useful in strengthening lower back and abdominal muscles and increasing stamina and physical endurance — all of which make you better equipped to handle the rigors of pregnancy.
Bikram yoga involves performing yoga in a room heated to 105 degrees Fahrenheit with a relative humidity of 60 to 70 percent. Although some doctors feel that this type of yoga is safe for pregnant women during the first trimester, prolonged exposure to high temperatures during the first trimester is inadvisable, given the possible risks of causing a neural tube defect. (See Book 2, Chapter 2 for more on neural tube defects, such as spina bifida.)
PRACTICING SAFE YOGA
Yoga can be a wonderful and relaxing way to work out while you’re pregnant but only if you exercise caution. Follow these tips when doing yoga during pregnancy:
· If you’re new to yoga, take a beginner class to ease yourself into a new exercise regime.
· Be careful about positions that stretch your muscles too much. Due to elevated levels of progesterone and relaxin (hormones produced during pregnancy), you can easily overstretch your muscles and ligaments.
· When bending forward, try to bend from the hips, not from the back. Also, try to lift your chest high to avoid putting extra pressure on your abdomen.
· After the middle of the second trimester, try to avoid performing poses that require you to lie flat on your back for extensive periods of time, because pressure from a pregnant uterus may decrease blood flow both to your heart and to the baby.
· As a general rule for any exercise, if you feel any pain or discomfort, stop and rest.