“A pregnant woman must eat for two”
Good nutrition during the 38 to 40 weeks of a normal pregnancy is essential for both mother and child. In addition to her normal nutritional requirements, the pregnant woman must provide nutrients and calories for the fetus, the amniotic fluid, the placenta, and the increased blood volume and breast, uterine, and fat tissue. Studies have shown a relationship between the mother’s diet and the health of the baby at birth. It is also thought that the woman who consumed a nutritious diet before pregnancy is more apt to bear a healthy infant than one who did not. Malnutrition of the mother is believed to cause decreased growth and mental retardation in the fetus. Low-birth-weight infants (less than 5.5 pounds) have a higher mortality (death) rate than those of normal birth weight.
WEIGHT GAIN DURING PREGNANCY
Weight gain during pregnancy is natural and necessary for the infant to develop normally and the mother to retain her health. In addition to the developing infant, the mother’s uterus, breasts, placenta, blood volume, body fluids, and fat must all increase to accommodate the infant’s needs (Table 11-1). The average weight gain during pregnancy is 25 to 35 pounds. During the first trimester of pregnancy, there is an average weight gain of only 2 to 4 pounds. Most of the weight gain occurs during the second and third trimesters of pregnancy, when it averages about 1 pound a week. This is because there is a substantial increase in maternal tissue during the second trimester, and the fetus grows a great deal during the third trimester. Weight gain varies, of course. A pregnant adolescent who is still growing should gain more weight than a mature woman of the same size. Underweight women should gain 28 to 40 pounds. Women of average weight should avoid excessive weight gain and try to stay within the 25- to 35-pound average gain. If the woman is pregnant with twins, then the recommended weight gain is 35 to 45 pounds. Overweight women can afford to gain less than the average woman, but not less than 15 pounds. No one should lose weight during pregnancy, because it could cause nutrient deficiencies for both mother and infant. On average, a pregnant adult requires no additional calories during the first trimester of pregnancy and only an additional 300 calories a day during the second and third trimesters.
Components of Weight Gain during Pregnancy, with Approximate Amounts of Gain
|COMPONENT||AMOUNT OF GAIN|
|Amniotic fluid||2 pounds|
|Blood volume||4 pounds|
|Maternal fat||4 pounds|
NUTRITIONAL NEEDS DURING PREPREGNANCY
Ideally when couples decide to have a child, they should make an appointment with their physician to discuss any health concerns or needed changes to the woman’s diet. At that time the physician needs to emphasize the importance of the woman taking a folic acid supplement at least 1 month prior to conception. During the 1990s, researchers established a correlation between taking folic acid before pregnancy and during the first trimester and having babies with brain and spinal cord defects. The results of this research led the U.S. government to require the addition of folic acid to grain products. The U.S. Public Health Service and the March of Dimes recommend that all women of childbearing age take a multivitamin or 400 g of folic acid daily. Lifestyle and habits also need to be taken into consideration before becoming pregnant. Certain medications, smoking, illegal drugs, and alcohol can all be detrimental to the embryo. Good nutrition is essential before becoming pregnant and during pregnancy.
NUTRITIONAL NEEDS DURING PREGNANCY
Some specific nutrient requirements are increased dramatically during pregnancy, as can be seen in Table 11-2. These figures are recommended for the general U.S. population; the physician may suggest alternative figures based on the client’s nutritional status, age, and activities. The protein requirement is increased by 20% for the pregnant woman over 25 and by 25% for the pregnant adolescent. Proteins are essential for tissue building, and protein-rich foods are excellent sources of many other essential nutrients, especially iron, copper, zinc, and the B vitamins.
Current research indicates there is no need for increased vitamin A during pregnancy. Excess vitamin A (more than 3,000 RE) has been known to cause birth defects such as hydrocephaly (enlargement of the fluid-filled spaces of the brain), microcephaly (small head), mental retardation, ear and eye abnormalities, cleft lip and palate, and heart defects. The required amount of vitamin D is 10 μg. The requirement for vitamin E is 15 mg μ-TE. The amount of vitamin K required is given as AI of 75 to 90 μg depending upon age, The requirements for all the water-soluble vitamins are increased during pregnancy. Additional vitamin C is needed to develop collagen and to increase the absorption of iron. The B vitamins are needed in greater amounts because of their roles in metabolism and the development of red blood cells. The requirements for the minerals calcium, iron, zinc, iodine, and selenium are all increased during pregnancy. Calcium is, of course, essential for the development of the infant’s bones and teeth as well as for blood clotting and muscle action. If the mother is not consuming adequate calcium in her diet, the baby will get its calcium from her bones. The need for iron increases because of the increased blood volume during pregnancy. In addition, the fetus increases its hemoglobin level to 20 to 22 grams per 100 ml of blood. This is nearly twice the normal human hemoglobin level of 13 to 14 mg per 100 ml of blood. The infant’s hemoglobin level is reduced to normal shortly after birth as the extra hemoglobin breaks down. The resulting iron is stored in the liver and is available when needed during the infant’s first few months of life, when the diet is essentially breast milk or formula. Therefore, an iron supplement is commonly prescribed during pregnancy. However, if the pregnant woman’s hemoglobin remains at an acceptable level without a supplement, the physician will not prescribe one.
FULFILLMENT OF NUTRITIONAL NEEDS DURING PREGNANCY
To meet the nutritional requirements of pregnancy, the woman should base her diet on MyPyramid. Special care should be taken in the selection of food so that the necessary calories are provided by nutrient-dense foods. One of the best ways of providing these nutrients is by drinking additional milk each day or using appropriate substitutes. The extra milk will provide protein, calcium, phosphorus, thiamine, riboflavin, and niacin. If whole milk is used, it will also contribute saturated fat and cholesterol and provide 150 calories per 8 ounces of milk. Fat-free milk contributes no fat and provides 90 calories per 8-ounce serving and thus is the better choice. To be sure that the vitamin requirements of pregnancy are met, obstetricians, nurse midwives, and physician’s assistants (PAs) may prescribe a prenatal vitamin supplement in addition to an iron supplement. However, it is not advisable for the mother to take any un-prescribed nutrient supplement, as an excess of vitamins or minerals can be toxic to mother and infant. The unusual cravings for certain foods during pregnancy do no harm unless eating them interferes with the normal balanced diet or causes excessive weight gain.
A pregnant woman is most likely to remain healthy and bear a healthy infant if she follows a well-balanced diet. Research has shown that maternal nutrition can affect the subsequent mental and physical health of the child. Anemia and PIH are two conditions that can be caused by inadequate nutrition. Caloric and most nutrient requirements increase for pregnant women (especially adolescents) and women who are breastfeeding. The average weight gain during pregnancy is 25 to 35 pounds.
Nutirtion and Diet by Ruth A. Roth