This will be a randomized clinical trial. Enrolled subjects will be randomized (1:1) into two study arms to receive either daily (Group 1) or alternate day (Group 2) supplementation with one oral pill containing ferrous sulfate with an equivalent elemental iron dose of 65 mg per pill.

During the enrollment (baseline) visit, subjects will undergo a blood draw to assess hemoglobin, ferritin and soluble transferrin receptor (sTfR) levels to confirm current depleted iron stores and will then be randomly allocated into one of the two study arms. All ferrous sulfate (oral tablets) will be provided to patients by the investigators. All subjects will be instructed to take oral iron on an empty stomach or 1 hour after meals for better absorption, preferably with a vitamin C rich product such as orange juice. To minimize variability introduced by other potential iron sources, prenatal vitamins that have the same amount and form of iron will be provided to both study groups.

Inclusion Criteria:

• Pregnant patients will be enrolled at less than 30 weeks gestational age (GA) with laboratory confirmed IDA (as defined by hemoglobin under 10.5 g/dL, as well as ferritin under 15 mcg/L)

Exclusion Criteria:

• Patients <18 years old, patients who have severe IDA that requires blood transfusion or IV iron infusion, patients who have other known hemoglobinopathy (such as thalassemia or sickle cell anemia) or anemia of different mechanism (such as vitamin B12 or folate deficiency), patients with ulcerative colitis, Crohn's disease, gastric ulcers, patients who have previously undergone gastric bypass surgery, patients who experience admission for antepartum bleed, have been diagnosed with abnormal placentation (i.e., placenta previa, placenta accreta, placenta increta or percreta)

pregnant women