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. 2023 Jun;117(6):1320-1330.
doi: 10.1016/j.ajcnut.2023.01.022. Epub 2023 May 12.

Hemoglobin distributions and prevalence of anemia in a multiethnic United States pregnant population

Wanhui Kang  1 , Carrie Irvine  2 , Yiqin Wang  1 , Andrew Clark  3 , Zhenglong Gu  1 , Eva Pressman  2 , Kimberly O O'Brien  4
Affiliations

Hemoglobin distributions and prevalence of anemia in a multiethnic United States pregnant population

Wanhui Kang et al. Am J Clin Nutr. 2023 Jun.

Abstract

Background: Few normative longitudinal hemoglobin data are available to estimate the prevalence and risk factors for anemia among a multiethnic United States pregnant population.

Objectives: The aim of this study was to characterize hemoglobin distributions and prevalence of anemia in a pregnant population receiving care at a large urban medical center.

Methods: A retrospective medical chart review was undertaken in 41,226 uncomplicated pregnancies of 30,603 pregnant individuals who received prenatal care between 2011 and 2020. Mean hemoglobin concentrations and anemia prevalence in each trimester and incidence of anemia during pregnancy in a subset of 4821 women with data in each trimester were evaluated in relation to self-reported race and ethnicity and other possible risk factors. Risk ratios (RRs) of anemia were determined using generalized linear mixed-effects models. Smoothed curves describing changes in hemoglobin across pregnancy were created using generalized additive models.

Results: The overall prevalence of anemia was 26.7%. The observed fifth percentiles of the hemoglobin distributions were significantly lower than the United States CDC anemia cutoffs in the second and third trimesters (T3). The RR (95% CI) of anemia were 3.23 (3.03, 3.45), 6.18 (5.09, 7.52), and 2.59 (2.48, 2.70) times higher in Black women than that in White women in each trimester, respectively. Asian women recorded the lowest risk of anemia compared with other racial groups in T3 (compared with White womenRR: 0.84; 95% CI: 0.74, 0.96). Hispanic women presented a higher risk of anemia in T3 than non-Hispanic women (RR: 1.36; 95% CI: 1.28, 1.45). In addition, adolescents, individuals with higher parity, and those carrying multiple fetuses experienced a higher risk of developing anemia in late gestation.

Conclusions: Anemia was evident in more than one-quarter of a multiethnic United States pregnant population despite current universal prenatal iron supplementation recommendations. Prevalence of anemia was higher among Black women and lowest among Asian and White women.

Keywords: anemia; electronic health records; hemoglobin; longitudinal data; multiethnicity; pregnancy; race and ethnicity.

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Figures

Figure 1
Figure 1
Flow chart of the study population identified from the retrospective medical chart review.
Figure 2
Figure 2
Hemoglobin concentrations across gestation in a multiethnic pregnant population receiving prenatal care in Rochester, NY, from 2011 to 2020. Smoothed curves were created using generalized additive models. Gray areas indicate the CI. Change in hemoglobin across gestation by anemia status (A). Change in hemoglobin concentrations across gestation by ethnic group (B). Mean hemoglobin concentrations across gestation by racial group (C). Mean hemoglobin concentrations across gestation by racial group in nonanemic pregnant individuals (D).
Figure 3
Figure 3
Hemoglobin distributions across gestation in a multiethnic pregnant population receiving prenatal care in Rochester, NY from 2011 to 2020 and in CDC reference population. Hemoglobin distributions in each trimester in a multiethnic pregnant population receiving prenatal care between 2011 and 2020 at Strong Memorial Hospital and Highland Hospital in Rochester, NY (A). Average hemoglobin concentrations (means and SEs) across gestation in the CDC reference population by the supplemental iron dose. Iron supplementation started at 12 or 16 weeks of gestation (B). aThe observed fifth percentile of the hemoglobin concentration in our population overlapped with the CDC anemia cutoff (11.0 g/dL) in the first trimester but significantly shifted to the left during the second and third trimesters of pregnancy.
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References

    1. Young M.F., Oaks B.M., Tandon S., Martorell R., Dewey K.G., Wendt A.S. Maternal hemoglobin concentrations across pregnancy and maternal and child health: a systematic review and meta-analysis. Ann. N. Y. Acad. Sci. 2019;1450(1):47–68. - PMC - PubMed
    1. Rahman M.M., Abe S.K., Rahman M.S., Kanda M., Narita S., Bilano V., et al. Maternal anemia and risk of adverse birth and health outcomes in low- and middle-income countries: systematic review and meta-analysis. Am. J. Clin. Nutr. 2016;103(2):495–504. - PubMed
    1. Daru J., Zamora J., Fernández-Félix B.M., Vogel J., Oladapo O.T., Morisaki N., et al. Risk of maternal mortality in women with severe anaemia during pregnancy and post partum: a multilevel analysis. Lancet Glob. Health. 2018;6(5):e548–e554. - PubMed
    1. Siu A.L., U.S. Preventive Services Task Force Screening for iron deficiency anemia and iron supplementation in pregnant women to improve maternal health and birth outcomes: U.S. Preventive Services Task Force recommendation statement. Ann. Intern. Med. 2015;163(7):529–536. - PubMed
    1. Auerbach M., Abernathy J., Juul S., Short V., Derman R. Prevalence of iron deficiency in first trimester, nonanemic pregnant women. J. Matern. Fetal. Neonatal Med. 2021;34(6):1002–1005. - PubMed

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