Optimal Ferritin Level Before Pregnancy
A ferritin level above 70 μg/L is ideal when entering pregnancy, as this level eliminates the need for iron supplementation and ensures adequate iron stores to meet the dramatically increasing demands of pregnancy. 1, 2, 3
Target Ferritin Thresholds
Women should aim for ferritin >70 μg/L before conception to avoid iron deficiency during pregnancy. 2, 3 This threshold represents adequate body iron reserves of approximately 500 mg, which only 15-20% of women naturally possess. 2
Stratification by Pre-Pregnancy Ferritin:
- Ferritin >70 μg/L: No iron supplementation needed during pregnancy 1, 2, 3
- Ferritin 31-70 μg/L: Requires 30-40 mg ferrous iron daily during pregnancy 2, 3
- Ferritin ≤30 μg/L: Requires 60-80 mg ferrous iron daily during pregnancy 2, 3
- Ferritin <15 μg/L: Indicates depleted iron reserves requiring therapeutic doses of 100 mg ferrous iron daily 2
Why This Matters for Pregnancy Outcomes
Iron requirements increase dramatically during pregnancy, from approximately 1.0 mg/day in the first trimester to 7.5 mg/day in the third trimester. 2 Starting pregnancy with inadequate stores creates a cascade of problems:
- Iron deficiency and iron deficiency anemia increase risks of preterm delivery, prematurity, and small-for-gestational-age birth weight 2
- Maternal iron deficiency negatively impacts infant intelligence and behavioral development 2
- Ferritin levels naturally decline throughout pregnancy, dropping from a mean of 56 ng/mL in the first trimester to 11.8 ng/mL in the third trimester even with supplementation 4
Current Status of Women of Childbearing Age
Approximately 40% of nonpregnant women of reproductive age have ferritin ≤30 μg/L, representing an unfavorable iron status for pregnancy. 2 This is largely due to menstrual blood loss, which averages 0.3-0.5 mg daily and results in women having significantly lower average ferritin levels (43 μg/L) compared to men (135 μg/L). 5, 6
Common Pitfalls:
- Waiting until pregnancy to assess iron status means missing the opportunity for optimal preconception repletion 2
- Relying on hemoglobin alone is inadequate, as ferritin is the most specific indicator of depleted iron stores 5
- A ferritin ≤15 μg/L confirms iron deficiency with 98% specificity in women of childbearing age, while ferritin <12 μg/L has 100% specificity 5
Practical Preconception Approach
Check ferritin levels before attempting conception rather than waiting for the first prenatal visit. 2, 3 If ferritin is suboptimal:
- For ferritin 31-70 μg/L: Start 30-40 mg ferrous iron daily for 2-3 months before conception 2
- For ferritin ≤30 μg/L: Start 60-100 mg ferrous iron daily for 3-6 months before conception 2
- Recheck ferritin after supplementation to confirm adequate repletion before pregnancy 3
Women with ferritin >70 μg/L entering pregnancy can take standard prenatal vitamins (containing 27 mg elemental iron) without additional supplementation, as this meets the Recommended Dietary Allowance and provides no additional benefit when stores are already adequate. 1