Suboptimal iron deficiency screening in pregnancy and the impact of socioeconomic status in a high-resource setting

Iron deficiency (ID) anemia in pregnancy is associated with poor maternal and childhood outcomes, yet ferritin testing, the standard test for ID, is not considered part of routine prenatal bloodwork in Canada. We conducted a retrospective cohort study of 44 552 pregnant patients with prenatal testing at community laboratories in Ontario, Canada, to determine the prevalence of ferritin testing over 5 years. Secondary objectives were to determine the prevalence and severity of ID and to identify clinical and demographic variables that influence the likelihood of ID screening. A total of 59.4% of patients had a ferritin checked during pregnancy; 71.4% were ordered in the first trimester, when the risk of ID is lowest. Excluding patients with abnormally elevated ferritins, 25.2% were iron insufficient (30-44 µg/L) and 52.8% were iron deficient (≤29 µg/L) at least once in pregnancy. A total of 8.3% were anemic (hemoglobin <105 g/L). The proportion of anemic patients with a subsequent ferritin test in pregnancy ranged from 22% to 67% in the lowest and highest anemia severity categories, respectively. Lower annual household income was negatively associated with the odds of a ferritin test; compared with those in the fifth (ie, highest) income quintile, the odds of ferritin testing for patients in the first, second, and fourth quintiles were 0.83 (95% confidence interval [CI], 0.74-0.91), 0.82 (95% CI, 0.74-0.91), and 0.86 (95% CI, 0.77-0.97), respectively. These data highlight gaps in prenatal care and issues of health equity that warrant harmonization of obstetrical guidelines to recommend routine ferritin testing in pregnancy.