Recommendations for weight gain in pregnancy are based on the woman’s prepregnancy weight for her height or her body mass index (BMI). BMI is calculated by dividing the weight in kilograms by the height in meters squared. Another method is to divide the weight in pounds by the height in inches squared and multiply the result by 703 (Centers for Disease Control and Prevention [CDC], 2009). Tables are available that show the BMI for various weights and heights.

Suggested gains vary according to the woman’s BMI (or weight for height) before pregnancy (Table 14-1). The recommended weight gain during pregnancy is 11.5 to 16 kg (25 to 35 lb) for women who begin pregnancy at normal BMI. The range allows for individual differences because no exact weight gain is appropriate for every woman.

Obesity is a growing problem. Obese women who become pregnant have an increased incidence of spontaneous abortion, gestational diabetes, gestational hypertension, preeclampsia, prolonged labor, cesarean birth, postpartum hemorrhage, wound complications, macrosomia, and congenital anomalies (Bond, 2011; Cunningham, Leveno, Bloom, et al., 2010; Stotland, 2009; Yogev & Catalano, 2009). Their children have an increased risk of childhood obesity (Josefson, 2011). Overweight and obese women should be advised to lose weight before conception to achieve the best pregnancy outcomes. The recommended weight gain for the obese woman is 5 to 9 kg (11 to 20 lb) to provide sufficient nutrients for the fetus.

Lower weight gain or weight loss for obese women during pregnancy is not recommended at this time as there is insufficient evidence about the effect on neurologic development of the infant. More research is needed in this area (Rasmussen & Yaktine, 2009)

In the past, women of small stature were advised to gain to the lower limits of the recommended range for their prepregnancy weight. Adolescents were advised to gain to the upper limits of their prepregnancy weight. However, evidence to support these guidelines has not been found. Therefore, these women should gain according to the recommendations for their BMI (Rasmussen & Yaktine, 2009).

Infants of a multifetal pregnancy are often born before term and tend to weigh less than infants born of single pregnancies. A greater weight gain in the mother may help prevent low birth weight. The recommended gain for women of normal prepregnancy weight who are carrying twins is 17 to 25 kg (37 to 54 lb) (Ramussen & Yaktine, 2009). When these women meet the recommended weight gain, they are less likely to deliver their twins before 32 weeks of gestation, and the infants are more likely to weigh more than 2500 gm (5.5 lb) (Fox, Rebarber, Roman, et al., 2010).

The pattern of weight gain is as important as the total increase. The general recommendation is for an increment of approximately 0.5 to 2 kg (1.1 to 4.4 lb) during the first trimester, when the mother may be nauseated and the fetus needs fewer nutrients for growth. During the rest of the pregnancy, the expected weekly weight gain for women of normal prepregnancy weight is 0.35 to 0.5 kg (0.8 to 1 lb) (Ramussen & Yaktine, 2009).

Women often wonder why they should gain so much weight when the fetus weighs so much less. Explaining the distribution of weight helps them understand this need (Figure 14-1).

Table 14-2 shows the current recommendations for DRIs for energy, carbohydrates, and protein for adult women.

Protein is necessary for metabolism, tissue synthesis, and tissue repair. The daily protein RDA for females is 46 g, depending on their age and size. During the second half of pregnancy, a protein intake of 71 g each day is recommended to expand the blood volume and support the growth of maternal and fetal tissues. This is an increase of 25 g of protein daily (Erick, 2012).

Protein is generally abundant in diets in most industrialized nations, but diets low in caloric intake may also be low in protein. If calories are low and protein is used to provide energy, fetal growth may be impaired.

The nurse should counsel women at risk for poor protein intake how to determine protein intake and increase food sources. When a woman needs to increase her intake, she should eat more protein-rich foods rather than use high-protein powders or drinks. Protein substitutes do not have the other nutrients provided by foods.

For most people, the daily intake of each vitamin is not always as high as recommended, but true deficiency states are uncommon in North America. Recommendations for vitamin intake and food sources are shown in Table 14-3.

The fat-soluble vitamins (A, D, E, and K) are stored in the liver. Deficiency states are not likely to occur, but fat-soluble vitamins can be toxic in excessive amounts. For example, too much vitamin A can cause fetal defects. The nurse should ask about vitamins and medications taken by pregnant women and alert them about the dangers of excess vitamins.

Water-soluble vitamins (B₆, B₁₂, and C, folic acid, thiamin, riboflavin, and niacin) are not stored in the body as well as fat-soluble vitamins. Therefore they should be included in the daily diet. Because excess amounts are excreted in the urine, there is less chance of toxicity from excessive intake, but it can occur with megadoses. These vitamins are easily transferred from food to water in cooking. Foods should be steamed, microwaved, or prepared in only small amounts of water. The remaining water can be used in other dishes, such as soups.

Folic acid (also called folate) can decrease the occurrence of neural tube defects, such as spina bifida and anencephaly, in newborns. It may also help prevent cleft lip, cleft palate, and some heart defects (CDC, 2010; Peckenpaugh, 2010). Adequate intake of folic acid is especially important just before conception and during the first trimester of pregnancy. Because about half of pregnancies are unplanned, all women of childbearing age should consume adequate amounts of folic acid each day. A Healthy People 2020 goal is for women of childbearing potential to take in at least 400 mcg of folic acid each day (U.S. Department of Health and Human Services, 2010).

In the past, the recommended amount of folic acid for women capable of childbearing has been 400 mcg (0.4 mg), but the U.S. Preventive Services Task Force (USPSTF) now recommends 400 mcg to 800 mcg (0.4 mg to 0.8 mg) each day. The dose should be taken for at least 1 month before conception and for 2 to 3 months after conception (USPSTF, 2009). There has been no change in the recommendation of 600 mcg (0.6 mg) of folic acid daily for the rest of pregnancy.

Women who are taking anticonvulsant drugs or who have previously had an infant born with a neural tube defect should take 4 mg daily before conception and during the first trimester (CDC, 2010; Johnson, Gregory, & Niebyl, 2007). This practice can decrease the risk of recurrence of neural tube defects by 80% (American Academy of Pediatrics [AAP] & American College of Obstetricians and Gynecologists [ACOG], 2007).

Women often do not realize the importance of folic acid in their diet before pregnancy begins, and many do not meet the recommended level, in spite of a national campaign to make the public more aware of this problem. One third of births occur to women age 18 to 24 years, but women in this group have lower intake of supplements containing folic acid and less knowledge of the need for folic acid than older women (CDC, 2008). More education is necessary to increase folic acid use in women of childbearing age. Because of its importance, folic acid is added to all enriched cereal grain products.

Most minerals are supplied in adequate amounts in normal diets. However, dietary intake of iron and calcium may be below recommended levels in women of childbearing age (Grodner, Roth, & Walkingshaw, 2012). Recommendations for mineral intake and food sources are shown in Table 14-3.

Water is important during pregnancy for the expanded blood volume and as part of the increased maternal and fetal tissues. Women should drink approximately 8 to 10 cups of fluids each day, with water constituting most of the fluid intake (Erick, 2012). Fluids low in nutrients should be limited because they are filling and replace other more nutritious foods and drinks.

The U.S. Department of Agriculture (USDA) has developed MyPlate, a food plan which provides a guide for healthy eating for adults and children. Guidelines for pregnancy and lactation are discussed below and summarized in Table 14-5. Pregnant or lactating women can go to the website www.choosemyplate.gov to get an individualized diet plan specifically adapted for them and their needs during pregnancy.

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