Iodine is also needed, and the recommended iodine allowance is 220 Lg/d (see Table 9-5). The use of iodized salt and bread products is recommended during pregnancy to ofset the increased fetal requirements and maternal renal losses of iodine. Despite this, iodine intake has declined substantially in the past 15 years, and in some areas it is probably inadequate (Casey, 2017). Severe maternal iodine deficiency predisposes ofspring to endemic cretinism, which is characterized by multiple severe neurological defects. In parts of China and Africa where this condition is common, iodide supplementation very early in pregnancy prevents some cretinism cases (Cao, 1994). To obviate this, many prenatal supplements now contain various quantities of iodine.
Cacium is retained by the pregnant woman during gestation and approximates 30 g. Most of this is deposited in the fetus late in pregnancy (Pitkin, 1985). his amount of calcium represents only approximately 2.5 percent of total maternal calcium, most of which is in bone and can readily be mobilized for fetal growth. s another potential use, routine calcium supplementation to prevent preeclampsia has not proved efective (Chap. 40, p. 727).
Zinc deficiency if severe may lead to poor appetite, suboptimal growth, and impaired wound healing. During pregnancy, the recommended daily intake approximates 12 mg. But, the safe level of zinc supplementation for pregnant women has not been clearly established. Vegetarians have lower zinc intakes (Foster, 2015). he bulk of studies support zinc supplementation only in zinc-deficient women in poor-resource countries (Nossier, 2015; Ota, 2015).
Manesium deficiency as a consequence of pregnancy has not been recognized. Undoubtedly, during prolonged illness with no magnesium intake, the plasma level might become critically low, as it would in the absence of pregnancy. We have observed magnesium deiciency during pregnancies in some with previous intestinal bypass surgery. As a preventive agent, Sibai and coworkers (1989) randomly assigned 400 normotensive primigravid women to 365-mg elemental magnesium supplementation or placebo tablets from 13 to 24 weeks' gestation. Supplementation did not improve any measures of pregnancy outcome.
Trace metals include copper, selenium, chromium, and manganese, which all have important roles in certain enzyme functions. In general, most are provided by an average diet. Selenium deficiency is manifested by a frequently fatal cardiomyopathy in young children and reproductive-aged women. Conversely, selenium toxicity resulting from oversupplementation also has been observed. Selenium supplementation is not needed in American women.
Potassium concentrations in maternal plasma decline by approximately 0.5 mEq/L by midpregnancy (Brown, 1986). Potassium deficiency develops in the same circumstances as in nonpregnant individuals-a common example is hyperemesis gravidarum.
Fluoride metabolism is not altered appreciably during pregnancy (Maheshwari, 1983). Horowitz and Heifetz (1967) concluded that no additional ofspring beneits accrued from maternal ingestion of luoridated water if the newborn ingested such water from birth. Sa Roriz Fonteles and associates (2005) studied microdrill biopsies of deciduous teeth and concluded that antenatal luoride provided no additional fluoride uptake compared with postnatal fluoride alone. Finally, supplemental luoride ingested by lactating women does not raise the luoride concentration in breast milk (Ekstrand, 1981).