At what week of pregnancy should a pregnant individual with a relatively low-risk pregnancy start taking iron and folate supplements?

Iron and Folate Supplementation in Pregnancy

All pregnant women should start taking 30 mg/day of elemental iron at their first prenatal visit, regardless of gestational age, and folic acid 400 mcg/day should ideally begin at least 4 weeks before conception and continue through the first 12 weeks of pregnancy. 1, 2

Iron Supplementation Timing and Dosing

Start iron supplementation immediately at the first prenatal visit:

• The CDC recommends initiating low-dose oral iron (30 mg/day elemental iron) at the first prenatal contact for all pregnant women as primary prevention against iron deficiency anemia 1, 2
• This recommendation applies regardless of which trimester the woman presents for care, as iron demands increase threefold during the second and third trimesters to approximately 5.0 mg iron/day 1
• Earlier initiation is more effective than higher doses started later—research demonstrates that beginning supplementation in the first trimester prevents deterioration of iron status more effectively than increasing doses in later pregnancy 3

Dose adjustments based on anemia status:

• For women without anemia: continue 30 mg/day throughout pregnancy 1, 2
• For women with confirmed iron deficiency anemia: increase to 60-120 mg/day of elemental iron 1, 2
• Once hemoglobin normalizes for gestational age, reduce back to maintenance dose of 30 mg/day 1, 2

Folic Acid Supplementation Timing and Dosing

Folic acid should begin preconceptionally, not just after pregnancy is confirmed:

• Standard-risk women: 400 mcg (0.4 mg) daily starting at least 4 weeks before planned conception through the first 12 weeks of pregnancy 1
• This timing is critical because neural tube closure occurs by 28 days post-conception, often before women know they are pregnant 1

High-risk women require higher doses:

• Women with BMI >30 kg/m², type 2 diabetes, personal/family history of neural tube defects, or taking antiseizure medications: 4-5 mg daily starting at least 12 weeks before conception 1
• After 12 weeks gestation, high-risk women can reduce to standard 400 mcg dose 1
• Always check vitamin B12 status before starting high-dose folic acid in women with diabetes or obesity 1

Combined Iron-Folate Therapy

Continue both supplements throughout pregnancy:

• While folic acid's primary benefit is neural tube defect prevention in early pregnancy, combined iron-folate therapy shows superior efficacy for treating anemia compared to iron alone 4
• Women receiving both iron and folate demonstrated hemoglobin increases of 1.42 g/dL versus 0.80 g/dL with iron alone after 60 days of treatment 4
• Folic acid supplementation during pregnancy may also increase gestational duration by approximately 1 week 5

Common Pitfalls to Avoid

Don't wait for anemia screening results to start iron:

• Begin 30 mg/day iron prophylactically at the first visit; screening is for detecting existing anemia that requires higher therapeutic doses 1, 2

Don't assume dietary intake is sufficient:

• Only one-fourth of women of childbearing age meet the recommended dietary allowance for iron through diet alone 1
• Most pregnant women cannot maintain adequate iron stores through diet and increased absorption alone, particularly in the second and third trimesters 1

Don't forget preconception counseling:

• Only 43% of women take folate before becoming pregnant, with lower rates among women under 21, smokers, and those from lower socioeconomic backgrounds 6
• Emphasize that folic acid must be started before conception for maximal neural tube defect prevention 1

Monitor for non-response:

• If hemoglobin doesn't increase by ≥1 g/dL or hematocrit by ≥3% after 4 weeks of treatment despite compliance, perform additional testing including MCV, RDW, and serum ferritin 1, 2
• Consider thalassemia minor or sickle cell trait in women of African, Mediterranean, or Southeast Asian ancestry with iron-refractory anemia 1