Nutrition During Pregnancy Part I: Weight Gain, Part II: Nutrient Supplements (1990) / Chapter Skim
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14 Iron Nutrition During Pregnancy
14 Iron Nutrition During Pregnancy
Pages 272-298
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From page 272... ...
During pregnancy, more iron is needed primarily to supply the growing fetus and placenta and to increase the maternal red cell mass (Hallberg, 1988~. Iron deficiency is common among pregnant women in industrialized countries, as shown by numerous studies in which hemoglobin concentrations during the last half of pregnancy were found to be higher in iron-supplemented women than in those given a placebo or no supplement (Table 14-1)
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From page 273... ...
273 Cal o ._ Ct Cal o ._ - o o a' so Ct o o ._ 4 C~ o Cal ED sit o ._ en o 3 To Cal Ct ._ D oc o Cal a: ._, D a o D Hi ,c, ._ o ; au C C Cat U
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From page 274... ...
This stage is the most difficult to define because it involves an arbitrary decision about how low iron stores should be before they are considered depleted. This is a particularly thorny issue with respect to pregnancy, because storage iron, estimated from bone marrow aspirates (or less directly by the serum ferritin)
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From page 275... ...
When the lowest hemoglobin concentration during any stage of pregnancy was below 10.0 g/dl, the likelihood of low birth weight, preterm birth, and perinatal mortality was increased. A hemoglobin concentration that was high during pregnancy (>13.0 g/dl)
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From page 276... ...
An association between a low maternal hemoglobin concentration at delivery and low birth weight can be expected since lower hemoglobin values are characteristic of an earlier stage of gestation. The infant of an iron-depleted mother has surprisingly little evidence of anemia or depletion of iron stores.
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From page 277... ...
Impaired iron status in either model can be considered to be equivalent to iron deficiency, taking into consideration that infection and chronic disease can be confounding factors by mimicking the laboratory abnormalities of iron deficiency. Among nonpregnant women between the ages of 20 and 44, estimated percentages of impaired iron status varied according to model used: 9.6 ~ 1.3% (standard error of the mean [SEMI)
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From page 278... ...
suggest that low socioeconomic status, low level of education, black or Hispanic background, and high parity were associated with iron deficiency (impaired iron status) in the MCV model for nonpregnant women (LSRO, 1984, 1989~.
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From page 279... ...
In NHANES II, the same prevalence of iron deficiency (impaired iron status) was found among black women, aged 20 to 44, as among whites in the same age group (5.7 ~ 0.9 and 5.0 ~ 0.6%, respectively)
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From page 280... ...
Users of oral contraceptives have substantially higher iron stores than do nonusers, based on serum ferritin values (Frassinelli-Gunderson et al., 1985~. In NHANES II, 18% of women aged 20 to 44 took oral contraceptives.
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From page 281... ...
Consumption of meals containing enhancers of iron absorption, such as meat and ascorbic acid-rich fruits and vegetables, and avoidance of strong inhibitors such as tea should do much to prevent iron deficiency (Monsen et al., 1978~. However, there is little information on the effectiveness of dietary counseling in preventing iron deficiency.
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From page 282... ...
This is a large amount of iron to accumulate over a 6-month period, especially when compared with the average total body iron content of 2,200 mg and the 1.3 mg of iron absorbed per day by nonpregnant women. Although 450 mg of iron for red cell production must be supplied during pregnancy, a large part of this can subsequently augment iron stores after a vaginal delivery, when the red cell mass decreases.
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From page 283... ...
In the absence of other laboratory evidence of iron deficiency, low serum ferritin is not associated with any deficits in physiologic function (Bothwell et al., 1979; Dallman, 1986~. For this reason, an acceptable goal for iron nutrition during pregnancy is simply to avoid progression beyond low iron stores (first stage of iron depletion)
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From page 284... ...
In the last trimester, the hemoglobin concentration gradually rises, reaching a mean value of 12.5 g'dl at 36 weeks of gestation. The World Health Organization criteria for anemia include a uniform value of <11.0 g/dl for all pregnant women instead of <12.0 g/dl, which is used for nonpregnant women (WEIO, 1968~.
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From page 285... ...
However, even if hemoglobin and serum ferritin values are normal early in pregnancy, this is no assurance that iron deficiency anemia or impaired hemoglobin production (Lewis and Rowe, 1986) will not develop later.
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From page 286... ...
Studies of women who donate blood regularly can provide data that are of relevance to pregnant women, because women who donate blood share many of the same characteristics with respect to low iron stores, increased iron requirements, and increased iron absorption. The average blood donation by a woman results in the loss of 200 mg of iron (Finch et al., 1977~.
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From page 287... ...
IRON 2~7 30 - o oa)
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From page 288... ...
These findings demonstrate the importance of additional research to test appropriate prenatal multinutrient supplements for in vivo bioavailability. Rough comparisons of iron absorption from various sup
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From page 289... ...
This enhancement may be surprising in view of the lack of a similar effect with ascorbic acid added to the much larger amounts of ferrous iron that are contained in supplements. Iron absorption is decreased if the fortified cereal product is rich in phytate (Hallberg et al., 1989~.
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From page 290... ...
, who determined the hemoglobin concentration and stainable iron in bone marrow at the beginning of the second trimester and at delivery in 20 women who were given 30 mg of iron per day as ferrous fumarate throughout that period. The hemoglobin concentration rose from an initial mean of 11.2 g/dl to a final value of 12.6 g/dl, and bone marrow iron at delivery equaled or exceeded the initial values.
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From page 291... ...
IRON 291 70 60 r:n 40 0' 13 12 g o o E I 11 _ , 7 ol ~I , , a_ _ ~ ~ 7 120 mg 30 mg ~ placebo 20 25 30 35 40 Week of Gestation as/ 30mg 1 20 mg ~ placebo 20 25 30 35 40 Week of Gestation FIGURE 14-3 Serum iron and hemoglobin levels in groups of 46 to 49 randomly assigned women receiving daily either a placebo or various doses of elemental iron as ferrous fumarate given orally. Data from groups receiving 60-mg oral doses of iron or 1 g of parenteral iron followed by 60-mg oral doses of iron per day are not shown but are similar to those of the iron-supplemented groups shown in the figure.
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From page 292... ...
The final hemoglobin concentration averaged 1.6 g/dl higher in the supplemented than in the unsupplemented group (among the highest differences observed in the studies summarized in Table 14-1~. Over this 24-week study period, the red cell mass increased by an average of approximately 450 ml in the supplemented group compared with 180 ml in the unsupplemented women, a difference of 270 ml.
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From page 293... ...
Anemia accompanied by a serum ferritin concentration of <12 ,ug/dl can be presumed to be iron deficiency anemia and requires treatment with 60 to 120 mg of ferrous iron daily. When the hemoglobin concentration becomes normal for the stage of gestation, the dose can be decreased to 30 mg/day.
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From page 294... ...
1979. The relationship between marrow iron stores, plasma ferritin concentrations and iron absorption.
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From page 295... ...
1977. Effect of blood donation on iron stores as evaluated by serum ferritin.
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From page 296... ...
1981. Serum ferritin as an assessment of iron stores and other hematologic parameters during pregnancy.
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From page 297... ...
1980a. Evaluation lay serum ferritin assay of the influence of maternal iron stores on the iron status of newborns and infants.
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From page 298... ...
1978. Serum ferritin and iron stores during pregnancy.
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