Progress in Chronic Disease Prevention Anemia during Pregnancy in Low-Income Women -- United States, 1987

Approximately 5% of nonpregnant women of reproductive age have anemia (1). Although anemia during pregnancy is associated with adverse outcomes (e.g., premature delivery, low birth weight, and fetal death) (2,3), the prevalence of anemia among pregnant women in the United States is not well defined.

Hematologic data from the 1987 CDC Pregnancy Nutrition Surveillance System (PNSS) (4) were used to characterize the pattern of anemia during pregnancy among a population of low-income women. The PNSS includes records of prenatal care submitted by public health and nutrition programs from 13 states* and the District of Columbia. In 1987, PNSS received records for 63,709 women aged 15-39 years. Most (95%) records were submitted by clinics of the Special Supplemental Food Program for Women, Infants, and Children (WIC)**. A hemoglobin (Hb) or hematocrit (Hct) value and a date of last menstrual period (LMP) were available for 58,066 (91%) women. Of these, 36,474 (63%) were white, and 21,572 (37%) were black. The race and age distributions were similar for those women for whom hematologic and LMP data were not available.

Cutoff values used to define anemia during each trimester of pregnancy were: first and third trimester--Hb less than 11 gm divided by L or Hct less than 33%; second trimester--Hb less than 10.5 gm divided by L or Hct less than 32% (5).

For both black and white women, the mean Hb and Hct values declined steadily during the first and second trimesters and reached nadir early in the third trimester. The mean values then increased slightly for the remainder of the third trimester (Figure 1 (Hct not shown)).

The prevalence of anemia increased during the second and third trimesters. The prevalence for white women and for black women, respectively, was 3.5% and 12.7% during the first trimester, 6.4% and 17.8% during the second, and 18.8% and 38.1% during the third.

Anemia was more prevalent among younger women, except for white women in the 35-39 age group. For all age groups, the prevalence of anemia was higher among black women than among white women (Figure 2).

Earlier enrollment in WIC was associated with a lower prevalence of anemia (Figure 3). For enrollment at all trimesters, black women had a higher prevalence of anemia than white women. Reported by: Div of Nutrition, Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note

Editorial Note: Among pregnant women who receive sufficient iron, Hb levels normally decrease early in pregnancy, then increase throughout the third trimester, ultimately attaining near prepregnancy levels (5,6). For women included in the PNSS, the incomplete rise of mean Hb levels (i.e., the failure to attain near prepregnancy levels) during the third trimester suggests that many of these women were iron deficient during pregnancy (6).

Hb values were lower among black women than among white women throughout pregnancy and may be related to a greater risk for iron deficiency in black women. However, differences in Hb and Hct levels by race--even when controlled for nutritional status--have been described previously, and the explanation for the difference observed in this analysis is unclear (7,8). The higher prevalences of anemia among young women during the third trimester and among those women who enrolled in public health programs during the second and third trimesters suggest that these groups are at a greater health and nutrition risk. It is possible that early enrollment in public health programs such as WIC may improve iron nutrition status during pregnancy and reduce the prevalence of anemia.

The high prevalence of anemia during the third trimester among women in the PNSS suggests that many low-income women have poor iron nutrition both before and during pregnancy. Further efforts to promote early enrollment in public health and nutrition programs, provide iron nutrition education, and ensure timely referral and follow-up of anemic women may lead to improved iron nutrition during pregnancy.

References

1. Dallman PR, Yip R, Johnson C. Prevalence and causes of anemia in the United States, 1976 to 1980. Am J Clin Nutr 1984;39:437-45.2. Murphy JF, Newcombe RG, O'Riordan J, Coles EC, Pearson JF. Relation of haemoglobin levels in first and second trimesters to outcome of pregnancy. Lancet 1986;1:992-4.

2. Garn SM, Ridella SA, Petzold AS, Falkner F. Maternal hematologic levels and pregnancy outcomes. Semin Perinatol 1981;5:155-62.

3. CDC. 1983 Annual summary of pediatric nutrition surveillance system. Atlanta: US Department of Health and Human Services, Public Health Service, 1985; HHS publication no. (CDC)85-8295.

4. CDC. CDC criteria for anemia in children and childbearing-aged women. MMWR 1989;38:400-4.

5. Puolakka J, Janne O, Pakarinen A, Jarvinen A, Vihko R. Serum ferritin as a measure of iron stores during and after normal pregnancy with and without iron supplements. Acta Obstet Gynecol Scand Suppl 1980;95:43-51.

6. Yip R, Schwartz S, Deinard AS. Hematocrit values in white, black, and American Indian children with comparable iron status. Am J Dis Child 1984;138:824-7.

7. Meyers LD, Habicht J-P, Johnson CL. Components of the difference in hemoglobin concentrations in blood between black and white women in the United States. Am J Epidemiol 1979;109:539-49. *Colorado, Connecticut, Florida, Illinois, Indiana, Kentucky, Maryland, Nebraska, Nevada, New Jersey, North Carolina, Oregon, and Utah. **The WIC program, designed to provide nutrition education and specific foods to children less than or equal to 5 years of age, lactating mothers, and pregnant and postpartum women, is closely associated with health-care delivery services.

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