Association between iron deficiency anemia and severe maternal morbidity: A retrospective cohort study

We examined the association between iron deficiency anemia (IDA) and severe maternal morbidity (SMM) during delivery and up to 1-year postpartum.

In a retrospective cohort study across 3 states, we computed adjusted relative risks (aRR) for SMM comparing individuals with IDA versus those without, using modified Poisson regression models.

Among 2459,106 individuals, 10.3 % (n = 252,240) had IDA. Individuals with IDA experienced higher rates of blood transfusion and non-transfusion SMM (329 and 122 per 10,000 deliveries, respectively) than those without IDA (33 and 46 per 10,000 deliveries, respectively). The risk of blood transfusion (aRR: 8.2; 95 % CI 7.9-8.5) and non-transfusion SMM (aRR: 1.9; 95 % CI: 1.8-2.0) were higher among individuals with IDA. The attributable risk per 10,000 deliveries due to IDA for blood transfusion and non-transfusion SMM during delivery were 29.5 (95 % CI: 28.9-30.0) and 5.7 (95 % CI: 5.3-6.2), respectively. Within 1-year postpartum, the relative risk of non-transfusion SMM (aRR:1.3; 95 % CI: 1.2-1.3) was 30 % higher among individuals with IDA.

IDA is associated with increased SMM risk. Addressing IDA in pregnant individuals may reduce SMM rates.