Maternal and Fetal Nutrition

Chapter 9


Maternal and Fetal Nutrition


Shannon E. Perry



Learning Objectives


On completion of this chapter, the reader will be able to:


• Explain recommended maternal weight gain during pregnancy.


• Compare the recommended level of intake of energy sources, protein, and key vitamins and minerals during pregnancy and lactation.


• Give examples of the food sources that provide the nutrients required for optimal maternal nutrition during pregnancy and lactation.


• Examine the role of nutrition supplements during pregnancy.


• List five nutritional risk factors during pregnancy.


• Compare the dietary needs of adolescent and mature pregnant women.


• Analyze examples of eating patterns of women from two different ethnic or cultural backgrounds and identify potential dietary problems.


• Assess nutritional status during pregnancy.


Nutrition is one of the many factors that influence the outcome of pregnancy (Fig. 9-1). However, maternal nutritional status is an especially significant factor, both because it is potentially alterable and because good nutrition before and during pregnancy is an important preventive measure for a variety of problems. These problems include birth of low-birth-weight (LBW) (birth weight of 2500 g or less) and preterm infants. Evidence is growing that a mother’s nutrition and lifestyle affect the long-term health of her children. Thus the importance of good nutrition must be emphasized to all women of childbearing potential. Key components of nutrition care during the preconception period and pregnancy include (Harnisch, Harnisch, and Harnisch, 2012):


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FIG 9-1 Factors that influence the outcome of pregnancy.



Nutrient Needs before Conception


The first trimester of pregnancy is a crucial one in terms of embryonic and fetal organ development. A healthful diet before conception is the best way to ensure that adequate nutrients are available for the developing fetus. Folate or folic acid intake is of particular concern in the periconception period. Folate is the form in which this vitamin is found naturally in foods, and folic acid is the form used in fortification of grain products and other foods and in vitamin supplements. Neural tube defects (failure in closure of the neural tube) are more common in infants of women with poor folic acid intake. Proper closure of the neural tube is required for normal formation of the spinal cord, and the neural tube begins to close within the first month of gestation, often before the woman realizes that she is pregnant (Box 9-1).



Box 9-1   Food Sources of Folate




Maternal and fetal risks in pregnancy are increased when the mother is significantly underweight or overweight when pregnancy begins. Ideally, all women would achieve their desirable body weights before conception.



Nutrient Needs during Pregnancy


Nutrient needs are determined, at least in part, by the stage of gestation. The amount of fetal growth varies during the different stages of pregnancy. During the first trimester, the synthesis of fetal tissues places relatively few demands on maternal nutrition. Therefore during the first trimester, when the embryo or fetus is very small, the needs are only slightly increased over those before pregnancy. In contrast, the last trimester is a period of noticeable fetal growth when most of the fetal stores of energy sources and minerals are deposited. Thus as fetal growth progresses during the second and third trimesters, the pregnant woman’s need for some nutrients increases greatly. Factors that contribute to the increase in nutrient needs include the following factors:



Dietary Reference Intakes (DRIs) (www.iom.edu) have been established for the people of the United States and Canada and are updated regularly. The DRIs include recommendations for daily nutritional intakes that meet the needs of almost all (97% to 98%) of the healthy members of the population. They are divided into age, sex, and life-stage categories (e.g., infancy, pregnancy, and lactation), and they can be used as goals in planning the diets of individuals (Table 9-1).



TABLE 9-1


RECOMMENDATIONS FOR DAILY INTAKES OF SELECTED NUTRIENTS DURING PREGNANCY AND LACTATION


































































































































NUTRIENT (UNITS) RECOMMENDATION FOR NONPREGNANT WOMAN* RECOMMENDATION FOR PREGNANCY* RECOMMENDATION FOR LACTATION* ROLE IN RELATION TO PREGNANCY AND LACTATION FOOD SOURCES
Energy (kilocalories [kcal] or kilojoules [kJ]†) Variable First trimester, same as nonpregnant; second trimester, nonpregnant needs + 340 kcal (1424 kJ); third trimester, nonpregnant needs + 452 kcal (1892 kJ) First 6 months, nonpregnant needs + 330 kcal (1382 kJ); second 6 months, nonpregnant needs + 400 kcal (1675 kJ) Growth of fetal and maternal tissues; milk production Carbohydrate, fat, and protein
Protein (g) 46 First trimester, same as nonpregnant; second and third trimesters, nonpregnant needs + 25 g‡ Nonpregnant needs + 25 g Synthesis of the products of conception; growth of maternal tissue and expansion of blood volume; secretion of milk protein during lactation Meats, eggs, cheese, yogurt, legumes (dry beans and peas, peanuts), nuts, grains
Water (L) in food and beverages 2.7 3 3.8 Expansion of blood volume, excretion of wastes; milk secretion Water and beverages made with water, milk, juices; all foods, especially frozen desserts, fruits, lettuce and other fresh vegetables
Fiber (g) 25 28 29 Promotes regular bowel elimination; reduces long-term risk for heart disease, diverticulosis, and diabetes Whole grains, bran, vegetables, fruits, nuts and seeds
Minerals
Calcium (mg) 1300/1000 1300/1000 1300/1000 Fetal skeleton and tooth formation; maintenance of maternal bone and tooth mineralization Milk, cheese, yogurt, sardines or other fish eaten with bones left in, deep green leafy vegetables except spinach or Swiss chard, calcium-set tofu, baked beans, tortillas
Iron (mg) 15/18 30 10/9 Maternal hemoglobin formation, fetal liver iron storage Liver, meats, whole grain or enriched breads and cereals, deep green leafy vegetables, legumes, dried fruits
Zinc (mg) 9/8 12/11 13/12 Component of numerous enzyme systems, possibly important in preventing congenital malformations Liver, shellfish, meats, whole grains, milk
Iodine (mcg) 150 220 290 Increased maternal metabolic rate Iodized salt, seafood, milk and milk products, commercial yeast breads, rolls, and donuts
Magnesium (mg) 360/310-320 400/350-360 360/310-320 Involved in energy and protein metabolism, tissue growth, muscle action Nuts, legumes, cocoa, meats, whole grains
Fat-Soluble Vitamins
A (mcg) 700 750/770 1200/1300 Essential for cell development, tooth bud formation, bone growth Dark green leafy vegetables, dark yellow vegetables and fruits, liver, fortified margarine and butter
D (mcg) 5 5 5 Involved in absorption of calcium and phosphorus, improves mineralization Fortified milk and breakfast cereals; salmon, tuna, and other oily fish; butter, liver
E (mg) 15 15 19 Antioxidant (protects cell membranes from damage), especially important for preventing breakdown of red blood cells (RBCs) Vegetable oils, green leafy vegetables, whole grains, liver, nuts and seeds, cheese, fish
Water-Soluble Vitamins
C (mg) 65/75 80/85 115/120 Tissue formation and integrity, formation of connective tissue, enhancement of iron absorption Citrus fruits, strawberries, melons, broccoli, tomatoes, peppers, raw dark green leafy vegetables
Folate (mcg) 400 600 500 Prevention of neural tube defects, increased maternal RBC formation Fortified ready-to-eat cereals and other grain products, green leafy vegetables, oranges, broccoli, asparagus, artichokes, liver
B6 or pyridoxine (mg) 1.2/1.3 1.9 2 Involved in protein metabolism Meats, liver, dark green vegetables, whole grains
B12 (mcg) 2.4 2.6 2.8 Production of nucleic acids and proteins, especially important in formation of RBCs and neural functioning Milk and milk products, eggs, meats, liver, fortified soy milk


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*When two values appear, separated by a diagonal slash, the first is for females younger than 19 years and the second is for those 19 to 50 years of age.


†The international metric unit of energy measurement is the joule (J). 1 kcal = 4.184 kJ.


‡Add an additional 25 g in twin pregnancies.


Data from Otten JJ, Helwig JP, Meyers LD, editors: Dietary reference intakes: the essential guide to nutrient requirements, Washington, DC, 2006, National Academies Press.



Energy Needs


Energy (kilocalories [kcal]) needs are met by carbohydrate, fat, and protein in the diet. No specific recommendations exist for the amount of carbohydrate and fat in the diet of the pregnant women, but the intake of these nutrients should be adequate to support the recommended weight gain. Although protein can be used to supply energy, its primary role is to provide amino acids for the synthesis of new tissues (see discussion later in this chapter). Longitudinal assessment of weight gain during pregnancy is the best way to determine whether the kcal intake is adequate; very underweight or active women may require more than the recommended increase in kcal to sustain the desired rate of weight gain.



Weight Gain


The desirable weight gain during pregnancy varies among women. The primary factor to consider in making a weight-gain recommendation is the appropriateness of the prepregnancy weight for the woman’s height—that is, whether the woman’s weight was normal before pregnancy or whether she was underweight or overweight. Whenever possible, the woman should achieve a weight in the normal range for her height before pregnancy. Maternal and fetal risks in pregnancy are increased when the mother is significantly underweight or overweight before pregnancy and when weight gain during pregnancy is either too low or too high. Severely underweight women are more likely to have preterm labor and to give birth to LBW infants. Both normal-weight and underweight women with inadequate weight gain have an increased risk for giving birth to an infant with intrauterine growth restriction (IUGR). Greater-than-expected weight gain during pregnancy may occur for many reasons, including multiple gestation, edema, gestational hypertension, and overeating. When obesity is present (either preexisting obesity or obesity that develops during pregnancy), there is an increased likelihood of macrosomia and fetopelvic disproportion; operative vaginal birth; emergency cesarean birth; postpartum hemorrhage; wound, genital tract, or urinary tract infection; birth trauma; and late fetal death. Obese women are more likely than normal-weight women to have preeclampsia and gestational diabetes.


A commonly used method of evaluating the appropriateness of weight for height is the body mass index (BMI), which is calculated by the following formula:


BMI=Weight÷Height2


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in which the weight is in kilograms and height is in meters. Thus for a woman who weighed 51 kg before pregnancy and is 1.57 m tall:


BMI=51 kg÷(1.57 m)2​, or 20.7


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Prepregnant BMI can be classified into the following categories: less than 18.5, underweight or low; 18.5 to 24.9, normal; 25 to 29.9, overweight or high; and greater than 30, obese (www.nhlbisupport.com/bmi). The BMI can be calculated on this website (see also Box 3-6).


At the first health care visit, the pregnant woman should be helped to establish a weight-gain goal for pregnancy that is suited to her prepregnancy weight. Progress toward this goal should be monitored at each visit.


For women with single fetuses, current recommendations are that women with normal BMI should gain 11.5 to 16 kg (25 to 35 lbs) during pregnancy (Fig. 9-2). Box 9-2 lists recommended weight gain for pregnancies with single fetuses, twin gestations, and multifetal (more than 2) gestations for women who are normal weight, underweight, and overweight.



Box 9-2   Weight Gain during Pregnancy




• Progressive weight gain during pregnancy is essential to ensure normal fetal growth and development and the deposition of maternal stores that promote successful lactation.


• Recommended weight gain during pregnancy is determined largely by prepregnancy weight for height. The recommended total weight gain is as follows: underweight women, 12.5 to 18 kg (28 to 40 lbs); normal-weight women, 11.5 to 16 kg (25 to 35 lbs); overweight women, 7 to 11.5 kg (15 to 25 lbs); and obese women 5 to 9 kg (11 to 20 lbs). For twin gestations, the recommended total weight gain is 21 to 28 kg (46 to 62 lbs) for women who are underweight before conception, 17 to 25 kg (37 to 54 lbs) for normal-weight women, 14 to 23 kg (31 to 50 lbs) for overweight women, and 11 to 19 kg (25 to 42 lbs) for obese women.


• There is not enough information available to make firm recommendations about optimal weight gain for women with more than 2 fetuses, but provisional recommendations have been made for all prepregnancy body mass index (BMI) categories except the underweight category (Institute of Medicine [IOM], 2009). The provisional recommendations for a gestation with more than 2 fetuses suggest that normal-weight women gain 17 to 25 kg, overweight women gain 14 to 23 kg, and obese women gain 11 to 19 kg.


• Weight gain should be achieved through a balanced diet of regular foods chosen from all the different food groups (see Table 9-3).


• The pattern of weight gain is important: approximately 0.5 kg per week during the second and third trimesters for underweight women, 0.4 kg per week for normal-weight women, 0.3 kg per week for overweight women, and 0.2 kg per week for obese women.


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FIG 9-2 Prenatal weight-gain chart for plotting weight gain for normal-weight women.


Pattern of Weight Gain


The optimal rate of weight gain depends on the stage of pregnancy. During the first and second trimesters, growth takes place primarily in maternal tissues; during the third trimester, growth occurs primarily in fetal tissues. During the first trimester of singleton pregnancy, the average total weight gain is only 1 to 2 kg. Thereafter the recommended weight gain increases to approximately 0.5 kg per week for an underweight woman and 0.4 kg per week for a woman of normal weight. The recommended weekly weight gain for overweight women during the second and third trimesters is 0.3 kg, and for obese women, 0.2 kg.


The recommended energy (kcal) intake corresponds to the recommended pattern of gain (see Table 9-1). There is no increment for the first trimester; an additional 340 kcal per day and 462 kcal per day over the prepregnant intake is recommended during the second and third trimester, respectively. These recommendations are most appropriate for singleton pregnancy and may need to be adjusted in multiple gestation. The amount of food providing the needed increase in energy is not large. The 340 additional kcal needed during the second trimester can be provided by one additional serving from any one of the following groups: milk, yogurt, or cheese (all skim milk products); fruits; vegetables; and bread, cereal, rice, or pasta. In the third trimester, an additional one third of a serving will provide the needed kcal.


The reasons for an inadequate weight gain (less than 1 kg per month for normal-weight women or less than 0.5 kg per month for obese women during the last two trimesters) or excessive weight gain (more than 3 kg per month) should be evaluated thoroughly. Possible reasons for deviations from the expected rate of weight gain, besides inadequate or excessive dietary intake, include measurement or recording errors or differences in weight of clothing or time of day. An exceptionally high gain is likely to be caused by an accumulation of fluids, and a gain of more than 3 kg in a month, especially after the twentieth week of gestation, often indicates the development of preeclampsia.



Hazards of Restricting Adequate Weight Gain


An obsession with thinness and dieting pervades the North American culture. Figure-conscious women may find it difficult to make the transition from guarding against weight gain before pregnancy to valuing weight gain during pregnancy. In counseling these women, the nurse can emphasize the positive effects of good nutrition as well as the adverse effects of maternal malnutrition (manifested by poor weight gain) on infant growth and development. This counseling includes information on the components of weight gain during pregnancy (Table 9-2) and the amount of this weight that will be lost at birth. Because lactation can help reduce maternal energy stores gradually, this also provides an opportunity to promote breastfeeding.



In the United States, 20% of women who give birth are obese (www.cdc.gov/reproductivehealth/MaternalInfantHealth/PregComplications.htm). Pregnancy is not a time for a weight-reduction diet. Even overweight or obese pregnant women need to gain at least enough weight to equal the weight of the products of conception (fetus, placenta, and amniotic fluid). If they limit their energy intake to prevent weight gain, they may also excessively limit their intake of important nutrients. Moreover, dietary restriction results in catabolism of fat stores, which in turn augments the production of ketones. The long-term effects of mild ketonemia during pregnancy are not known, but ketonuria is associated with the occurrence of preterm labor. It should be stressed to obese women (and to all pregnant women) that the quality of the weight gain is important, with emphasis placed on the consumption of nutrient-dense foods and the avoidance of empty-calorie foods (see Critical Thinking Case Study).



image Critical Thinking Case Study


Nutrition and the Overweight Pregnant Woman


Tamara, age 27, of African-American and Asian heritage, is 3 months pregnant and comes to her initial appointment for diagnosis and care. She appears to be overweight for her height (5′ 6″ tall, 172 lbs [78 kg]). To provide optimal care for her, you plan to calculate her prepregnancy body mass index (BMI). When her pregnancy is confirmed, you are asked to plan a diet with Tamara that meets the minimum daily requirements and allows for growth of the pregnancy. You know that it is important to include consideration of personal preferences and cultural factors in your plan. With Tamara, identify barriers to implementing the plan.




Excessive Weight Gain


Weight gain is important, but pregnancy is not an excuse for uncontrolled dietary indulgence. The woman should place an emphasis on the quality of her food intake as she considers her needs and those of her fetus. Excessive weight gained during pregnancy may be difficult to lose after pregnancy, thus contributing to chronic overweight or obesity—an etiologic factor in a host of chronic diseases, including hypertension, diabetes mellitus, and arteriosclerotic heart disease. The woman who gains 18 kg or more is especially at risk (Box 9-3). Food energy intake and particularly intake of fat is likely to be high among pregnant women, especially low-income women (see Evidence-Based Practice box).



Box 9-3


Bariatric Obstetric Care


Obstetricians today are seeing more morbidly obese pregnant women—those who weigh 400, 500, and even 600 pounds. Obesity creates many risks for pregnant women, including hypertension, diabetes, and prematurity. To manage their conditions and to meet their logistical needs, a new medical subspecialty—bariatric obstetrics—has arisen. Extra-wide blood pressure cuffs, scales that can accommodate up to 880 pounds, and extra-wide surgical tables designed to hold the weight of these women are used. Special techniques for ultrasound examination and longer surgical instruments for cesarean birth are required. In the bariatric obstetric clinic at St. Louis University in St. Louis, Missouri, women are counseled to avoid gaining weight and even to lose weight during pregnancy. New evidence indicates that when obese women maintain or lose weight during pregnancy, they have fewer complications and give birth to healthier babies.


From Paul AM: Too fat and pregnant, New York Times, July 13, 2008.



Evidence-Based Practice


Weight Management in Pregnancy






Critically Analyze the Evidence




• Obesity in pregnancy is associated with offspring with attention deficit hyperactivity disorder (ADHD) in childhood, eating disorders in adolescence, and psychotic disorders in adulthood (Van Lieshout, Taylor, and Boyle, 2011).


• Weight-management interventions for obese pregnant women result in significantly decreased weight gain and in significantly less preeclampsia and shoulder dystocia (Thangaratinam, Rogozinska, Jolly, et al., 2012).


• The most effective interventions were dietary resulting in decreased risk for preeclampsia, gestational hypertension, and preterm birth, with no harm to the fetus (Thangaratinam, Rogozinska, Jolly, et al., 2012).


• In a systematic review, researchers found that goal setting was a useful technique for achieving optimal weight gain. Obese women may require further counseling (Brown, Sinclair, Liddle, et al., 2012).


• Regular activity improved maternal glycemic control and fetal outcomes. Caregivers should recommend physical activity to most pregnant women as safe and beneficial (Ferraro, Gaudet, and Adamo, 2012).



Apply the Evidence: Nursing Implications




• Preconceptional counseling should include prevention of obesity, ideally from childhood. Obese women are at risk for cardiac and pulmonary diseases, gestational hypertension and diabetes, and obstructive sleep apnea. Obesity in pregnancy may result in higher risk for congenital anomalies, operative birth, and surgical complications (Davies, Maxwell, McLeod, et al., SOGC, 2010).


• Nurses are frequently the main educators for their pregnant patients. Counseling obese pregnant women about nutrition and food choices and using collaborative goal setting for weight gain can prevent pregnancy risks and avoid weight gain that may persist beyond pregnancy.


• Activity needs to be frequent, fun, and affordable. An excellent idea is encouraging the woman to walk with other pregnant women, which provides social support and increased safety. In addition, the nurse can advocate for low-cost indoor facilities in the community.




References



Brown, MJ, Sinclair, M, Liddle, D, et al. A systematic review investigating healthy lifestyle interventions incorporating goal setting strategies for preventing excess gestational weight gain. PLoS One. 2012; 7(7):e39503.


Davies, GA, Maxwell, C, McLeod, L, et al. Society of Obstetricians and Gynaecologists of Canada (SOGC): Obesity in pregnancy. J Obstet Gynaecol Can. 2010; 32(2):165–173.


Ferraro, ZM, Gaudet, L, Adamo, KB. The potential impact of physical activity during pregnancy on maternal and neonatal outcomes. Obstet Gynecol Surv. 2012; 67(2):99–110.


Thangaratinam, S, Rogozinska, E, Jolly, K, et al. Interventions to reduce or prevent obesity in pregnant women: a systematic review. Health Technol Assess. 2012; 16(31):1–192.


Van Lieshout, RJ, Taylor, VH, Boyle, MH. Pre-pregnancy and pregnancy obesity and neurodevelopmental outcomes in offspring: a systematic review. Obes Rev. 2011; 12(5):e548–559.


*Adapted from Quality and Safety Education for Nurses (QSEN) at www.qsen.org/.



Protein


Protein, with its essential constituent nitrogen, is the nutritional element basic to growth. Adequate protein intake is essential to meet increasing demands in pregnancy.


These demands arise from:



Milk, meat, eggs, and cheese are complete protein foods with a high biologic value. Legumes (dried beans and peas), whole grains, and nuts are also valuable sources of protein. In addition, these protein-rich foods are a source of other nutrients such as calcium, iron, and B vitamins. Plant sources of protein often provide needed dietary fiber. The recommended daily food plan (Table 9-3) is a guide to the amounts of these foods that would supply the quantities of protein needed. The recommendations provide for only a modest increase in protein intake (25 g daily) over the prepregnant levels in adult women.



TABLE 9-3


DAILY FOOD GUIDE FOR PREGNANCY AND LACTATION
































FOOD GROUP DAILY AMOUNT OF FOOD RECOMMENDED FOR WOMEN* SERVING SIZE
Grains 6- to 8-ounce equivalents
At least half of grain servings should be whole grains. Whole grains are those that contain the entire grain kernel (bran, germ, endosperm) (e.g., whole wheat or cornmeal, oatmeal, and brown rice).
Refined grains have been milled to remove the bran and germ (e.g., white flour, white bread, degermed cornmeal, white rice, and corn or flour tortillas).		 1-ounce equivalent = 1 slice bread, 1 cup ready-to-eat cereal, or ½ cup cooked rice or pasta or cooked cereal
Vegetables
Vary the vegetables consumed to take advantage of the different nutrients they offer		 2½ to 3 cups
Weekly intake should include at least the following: 3 cups dark green vegetables (e.g., spinach or greens, broccoli, bok choy, romaine lettuce); 2 cups orange vegetables (e.g., carrots; acorn, butternut, or Hubbard squash; sweet potatoes); 3 cups dry beans or peas (e.g., black, navy, or kidney beans; chickpeas; black-eyed peas; split peas; lentils; soybeans; tofu); 3 cups starchy vegetables (corn, green peas, potatoes); and 6½ cups of other vegetables (e.g., artichokes, asparagus, bean sprouts, green beans, cauliflower, cucumber, tomatoes, iceberg or head lettuce).		 1 cup = 2 cups raw leafy greens; 1 cup of other vegetables, raw or cooked; or 1 cup of vegetable juice
Fruits 2 cups 1 cup = 1 cup raw, frozen, or canned fruit; 1 cup 100% juice; or ½ cup dried fruit
Milk, yogurt, and cheese (milk group) 3 cups
Most milk group choices should be fat free or low fat.		 1 cup = 1 cup milk or yogurt; 1½ ounces natural cheese; 2 ounces processed cheese (e.g., American); 2 cups cottage cheese; 1½ cups ice cream (choose fat-free or low-fat most often)
Meat, poultry, fish, dry beans, eggs, and nuts (meat and beans† groups) 5½- to 6½-ounce equivalents
Most meat and poultry choices should be lean or low fat. Fish, nuts, and seeds contain healthy oils, so choose these foods frequently instead of meat or poultry.		 1 ounce-equivalent = 1 ounce (30 g) meat, poultry, or fish; ¼ cup cooked dried beans†; 1 egg; 1 tablespoon (15 mL) peanut butter; ½ ounce nuts or seeds
Oils 6 teaspoons (30 mL)
Choose oils rather than solid fats. Solid fats are fats that are solid at room temperature, such as butter, shortening, stick margarine, and pork, chicken, or beef fat. Read the label: choose products with no trans fats, limit intake of saturated fats, and choose oils high in monounsaturated and polyunsaturated fats.		 1 teaspoon = 1 teaspoon liquid oil (e.g., olive, canola, sunflower, safflower, peanut, soybean, cottonseed) or soft margarine (tub or squeeze bottle); 1 tablespoon mayonnaise or Italian salad dressing; ¾ tablespoon Thousand Island salad dressing; 8 large olives; ⅙ medium avocado; ⅓ ounce dry roasted peanuts, mixed nuts, cashews, sunflower seeds†

*These are approximate amounts based on a relatively sedentary lifestyle and should be individualized. Intake may have to be increased for women with a more active lifestyle or multiple gestation, those who are underweight before pregnancy, or those exhibiting poor gestational weight gain. Needs during lactation may also be greater than these recommendations.


†Beans are also part of the vegetable group; avocados are also part of the fruit group, and nuts and seeds are part of the meat and beans group.


Protein intake in many people in the United States is relatively high; thus many women may not need to increase their protein intake at all during pregnancy. Three servings of milk, yogurt, or cheese (four for adolescents) and two servings (5 to 6 oz [140 to 168 g]) of meat, poultry, or fish would supply most of the recommended protein for a pregnant woman. Additional protein is provided by vegetables and breads, cereals, rice, or pasta. Pregnant adolescents, women from impoverished backgrounds, and women adhering to unusual diets such as a macrobiotic (highly restricted vegetarian) diet are those whose protein intake is most likely to be inadequate. High-protein supplements are not recommended because they have been associated with an increased incidence of preterm births.


Pregnant and nursing women should be especially careful when choosing fish to select those that are low in mercury.



image Safety Alert


High levels of mercury can harm the developing nervous system of the fetus or young child, and certain fish are especially high in mercury. Women who may become pregnant, women who are pregnant or nursing, and young children need to follow some precautions: (1) avoid eating shark, swordfish, king mackerel, and tilefish; (2) check local advisories about the safety of fish caught by family and friends in local bodies of water, but if no advisory is available, limit intake of these fish to 6 ounces and eat no other fish that week; and (3) eat as much as 12 ounces a week of a variety of commercially caught fish and shellfish low in mercury, such as shrimp, salmon, pollock, catfish, and canned light tuna (but limit intake of albacore or “white” tuna and tuna steaks, which contain more mercury, to 6 ounces per week). Additional information about mercury levels in a variety of commercial fish is available at www.cfsan.fda.gov/~frf/sea-mehg.html.



Fluids


Water is the main substance of cells, blood, lymph, amniotic fluid, and other vital body fluids. It is essential during the exchange of nutrients and waste products across cell membranes. It also aids in maintaining body temperature. A good fluid intake promotes regular bowel function, which is sometimes a problem during pregnancy. The recommended daily intake is about 8 to 10 glasses (2.3 L) of fluid. Water, milk, and decaffeinated tea are good sources. Foods in the diet should supply an additional 700 mL or more of fluid. Dehydration may increase the risk for cramping, contractions, and preterm labor.


The safety of caffeine use in pregnancy is an important consideration. Some investigators (e.g., Weng, Odouli, and Li, 2008) but not others (e.g., Pollack, Louis, Sundaram, et al., 2010) found that women who consume more than 200 mg of caffeine daily (equivalent to about 12 oz of coffee) may be at increased risk for miscarriage. Data also suggest that excess caffeine intake may contribute to IUGR. In their review, Jahanfar and Sharifah (2009) found that there is insufficient evidence to determine whether caffeine has any effect on pregnancy outcome. Although the evidence about caffeine is far from conclusive, the March of Dimes recommends a daily intake of no more than 200 mg of caffeine (March of Dimes, 2010). Caffeine is found not only in coffee but also in tea, some soft drinks, and chocolate (Table 9-4).


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Sep 16, 2016 | Posted by in NURSING | Comments Off on Maternal and Fetal Nutrition

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