FIGURE 9-5 Cumulative kilocalories required for pregnancy. (Redrawn of ordinary nonpregnant requirements plus those speciic to from Chamberlain G, Broughton-Pipkin F (eds): Clinical Physiology in pregnancy. For example, the additional energy required during Obstetrics, 3rd ed. Oxford, Blackwell Science, 1998.) increased maternal blood volume (Chap. 4, p. 55). During the second half of pregnancy, approximately 1000 g of protein are deposited, amounting to 5 to 6 g/d (Hytten, 1971). To accomplish this, protein intake that approximates 1 g/kg/ d is recommended (see Table 9-5). Data suggest this should be doubled in late gestation (Stephens, 2015). Most amino-acid levels in maternal plasma fall markedly, including ornithine, glycine, taurine, and proline (Hytten, 1991). Exceptions during pregnancy are glutamic acid and alanine, the concentrations of which rise.
Preferably, most protein is supplied from animal sources, such as meat, milk, eggs, cheese, poultry, and fish. hese furnish amino acids in optimal combinations. Milk and dairy products are considered nearly ideal sources of nutrients, especially protein and calcium, for pregnant or lactating women. Ingestion of specific ish and potential methylmercury toxicity are discussed on page 170.
The intakes recommended by the Institute of Medicine (2006) for various minerals are listed in Table 9-5. With the exception of iron and iodine, practically all diets that supply suicient calories for appropriate weight gain will contain enough minerals to prevent deiciency.
Iron requirements are greatly increased during pregnancy, and reasons for this are discussed in Chapter 4 (p. 58). Of the approximately 300 mg of iron transferred to the fetus and placenta and the 500 mg incorporated into the expanding maternal hemoglobin mass, nearly all is used after midpregnancy. During that time, iron requirements imposed by pregnancy and maternal excretion total approximately 7 mg/ d (Pritchard, 1970). Few women have suicient iron stores or dietary intake to supply this amount. Thus, the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (20e17) endorse the recommendation by the National Academy of Sciences that at least 27 mg of elemental iron be supplemented daily to pregnant women. his amount is contained in most prenatal vitamins.
Scott and coworkers (1970) established that as little as 30 mg of elemental iron, supplied as ferrous gluconate, sulfate, or fumarate and taken daily throughout the latter half of pregnancy, provides suicient iron to meet pregnancy requirements and protect preexisting iron stores. his amount will also provide for iron requirements of lactation. he pregnant woman may benefit from 60 to 100 mg of elemental iron per day if she is large, has a multifetal gestation, begins supplementation late in pregnancy, takes iron irregularly, or has a somewhat depressed hemoglobin level. he woman who is overtly anemic from iron deficiency responds well to oral supplementation with iron salts. In response, serum ferritin levels rise more than the hemoglobin concentration (Daru, 2016).