The mechanisms underlying the association of low maternal Hb with birth outcomes are complex and multifactorial and may include nutritional deficiencies (e.g., iron, vitamin A, folic acid, or vitamin B12 deficiency), infectious causes (e.g., malaria, schistosomiasis, hookworm infection, HIV), hemoglobinopathies (sickle cell anemia, thalassemia), and inflammation [172]. Here, GSTM1 is linked to sickle cell disease.