Anemia During Pregnancy in a U.S. Nationwide Cohort, 2018-2023

Anemia increases the risk of adverse perinatal outcomes, yet prevalence estimates in the United States are limited by selective samples or low sensitivity of diagnosis codes. We assessed the prevalence of anemia during pregnancy by analyzing hemoglobin and hematocrit values using trimester-specific standards in a longitudinal nationwide cohort of commercially insured individuals who gave birth from 2018 to 2023. We included individuals with laboratory values measured during routine screening (4 weeks to less than 14 weeks of gestation and 22 weeks to less than 30 weeks of gestation). The prevalence of anemia during pregnancy was 25.6% (95% CI, 25.3-25.9%). At prenatal care initiation (4 weeks to less than 14 weeks of gestation) and mid-pregnancy (22 weeks to less than 30 weeks of gestation) measurements, 4.3% (95% CI, 4.1-4.4%) and 24.5% (95% CI, 24.2-24.8%) of individuals had anemia, respectively. These findings demonstrate anemia during pregnancy is a public and population health issue.