LB2882MaternalNutriti+ - Mead Johnson Nutrition

Iron
Iron is vital to the production of hemoglobin, (which is necessary for oxygen transport), and energy production,
fetal immunity, and development of the central nervous system. 106 Iron deficiency affects more than 2 billion people
globally, making it the most common nutrient deficiency in the world. Iron deficiency is more common in developing
countries but continues to be a significant problem in developed countries despite near elimination of other forms
of malnutrition. 107 An estimated eight million women of childbearing age in the US have iron-deficiency anemia, 2 and
it is reasonable to expect that a large number of women are also iron-deficient. Low-income, less than 12 years of
education and increased parity are all associated with a greater risk of iron deficiency and iron-deficiency anemia. 42,108
The global prevalence of iron-deficiency anemia is estimated to be 47.4% in pregnant women. 18
The recommended iron intakes established by the IOM increase from 18 mg/day to 27 mg/day during pregnancy
for women ages 19 to 50 years 20 while the WHO has established different recommended intakes based on the
bioavailability of dietary iron consumed. In developing countries, it is reasonable to use iron bioavailability levels of 5%
and 10% translating into recommended nutrient intakes for lactating women of 30 and 15 mg/day respectively. In
developed countries consuming a more Western diet, it is more appropriate to use bioavailability levels of 12% and
15%, translating into recommended nutrient intakes for lactating women of 12.5 and 10 mg/day of iron, respectively.
The WHO establishes no recommended nutrient intakes for iron in pregnant women because the iron balance in the
diet depends on amounts of stored iron in addition to the bioavailability of dietary iron. 21
Iron stores at the time of conception are a strong indicator of risk for iron-deficiency anemia later in pregnancy. 42
Serum ferritin levels are a measure of stored iron in the body and can be used with a hematocrit to confirm irondeficiency
anemia when there is no evidence of inflammation 108 before and during pregnancy. Iron-deficiency anemia
during pregnancy has been associated with an increased risk for preterm birth, low birth weight, and perinatal
mortality. 109-111 However, results of recent studies on the effects of maternal iron status and supplementation during
pregnancy on fetal growth have been inconsistent. In a recent review on iron supplementation and pregnancy
outcome, studies starting supplementation in mid- or late pregnancy found an increase in maternal iron markers,
but no effect on fetal growth with the exception of one study where high-dose supplementation showed a
positive association with birth length (not with birth weight) in a low-income setting. However, in studies starting
supplementation in early pregnancy, maternal iron status did not improve, but there was a beneficial effect on fetal
growth. 112
Iron absorption during pregnancy is determined by several factors including the amount and bioavailability of
dietary iron as well as the changes in iron absorption that occur during pregnancy. Although there is an increase in
iron absorption, it is difficult for the mother to consume enough dietary iron to meet her iron requirements during
pregnancy. 21 The typical American diet provides inadequate iron to meet the recommendations for the pregnancy
state. 113 In addition, the endogenous iron stores of women may be insufficient to provide for the increased iron
demands of pregnancy. 65
In the US, the CDC recommends that all pregnant women take 30 mg of supplemental elemental iron every day
to prevent anemia 2 and 60 to 120 mg of elemental iron daily to treat anemia once it is diagnosed. 2,113 In the UK,
prophylactic iron supplementation is not recommended for pregnant women. However, pregnant women are
monitored throughout pregnancy for iron-deficiency anemia and recommendations for supplementation based on iron
status tests are established. 107 There is some concern that such prophylactic iron supplementation in women without
anemia or iron-deficiency anemia may increase the risk of pregnancy complications. 42 However, iron supplementation
during pregnancy has merit, as a large proportion of women have difficulty maintaining iron stores during pregnancy
and are at risk for anemia. 113 The WHO recommends that pregnant women be supplemented with 60 mg iron in
conjunction with 400 µg of folic acid daily. 18
19