Figure 1.

Causal diagram depicting the relationships between ferritin levels/iron deficiency and hemoglobin (Hb) levels/anemia at enrollment, birth, 6 months postpartum, and 12 months postpartum

Potential confounders, presented as a single node in the blue box, include age, gravidity, mid-upper arm circumference (MUAC), location of enrollment clinic, smoking status, history of fever, Plasmodium spp. infection, and red blood cell (RBC) polymorphisms. Vertical dashed arrows depict associations between concurrent iron stores and Hb levels/anemia—the key associations of interest. Adherence to iron supplements was not included as it is not a common cause confounder and was only recorded at a single time point (birth).