Why is ferritin measurement important in the evaluation of infertility?

Ferritin Screening in Infertility Evaluation

Ferritin measurement is important in infertility evaluation because iron deficiency (ferritin <30 μg/L) is significantly more prevalent in infertile women and is associated with worse pregnancy outcomes, including higher miscarriage rates and lower live birth rates.

Why Ferritin Matters: The Evidence

While major infertility guidelines from the EAU (2025) 1 and AUA/ASRM (2024) 2 do not currently include ferritin as part of standard male or female infertility workup, emerging research demonstrates compelling associations that warrant clinical attention:

Key Clinical Associations

In women with unexplained infertility:

• Iron deficiency (ferritin <30 μg/L) occurs in 33.3% of infertile women versus only 11.1% of fertile controls 3
• Ferritin <30 μg/L is independently associated with unexplained infertility (OR 4.9) 3
• Women with recurrent pregnancy loss have significantly lower ferritin levels (39.9 μg/L vs 62.2 μg/L in controls) and higher prevalence of iron deficiency (35.7% vs 13.7%) 4

Treatment outcomes are striking:

• After correcting iron deficiency with IV ferric carboxymaltose, conception rates increased from 65% to 77% 5
• Live birth rates more than doubled from 26% to 51% after iron repletion 5
• Miscarriage rates dropped from 28% to 13% following iron treatment (OR 0.32 for miscarriage after treatment) 5
• These benefits persisted after adjusting for age and ART method 5

Mechanistic Understanding

Iron deficiency affects reproductive function through multiple pathways:

• Ferroportin (iron export protein) mRNA is downregulated in granulosa cells from infertile women, suggesting disrupted iron homeostasis at the cellular level 6
• Iron is essential for cellular energy metabolism, DNA synthesis, and oxidative stress regulation—all critical for oocyte quality and embryo development
• The inverse relationship between ferritin levels and number of previous pregnancy losses suggests iron deficiency reflects more severe reproductive disturbance 4

Clinical Application Algorithm

When to check ferritin:

1. All women presenting with unexplained infertility
2. Women with recurrent pregnancy loss (≥2 losses)
3. Couples with failed ART cycles
4. Women with heavy menstrual bleeding and infertility

Diagnostic threshold:

• Use ferritin <30 μg/L as the cutoff for iron deficiency in reproductive-age women 5, 3
• This is higher than the traditional anemia threshold of 15 μg/L and reflects functional iron deficiency relevant to reproduction

Treatment approach:

• For ferritin <30 μg/L: Consider iron supplementation (oral or IV depending on severity and tolerance)
• IV iron (ferric carboxymaltose 500 mg) shows robust evidence for improving reproductive outcomes 5
• Recheck ferritin after treatment to confirm repletion (target >30 μg/L, ideally 50-80 μg/L)

Important Caveats

Limitations of current evidence:

• A 2024 Mendelian randomization study found no genetic causal relationship between iron status and infertility 7, suggesting the association may be complex or mediated through non-genetic mechanisms
• Most evidence comes from observational studies; large randomized trials are lacking
• Current major guidelines do not yet incorporate ferritin screening, reflecting the evolving nature of this evidence

Practical considerations:

• Ferritin is an acute phase reactant—interpret cautiously in presence of inflammation or infection
• The association is strongest in women; male fertility and iron status relationships are less established
• Iron deficiency often coexists with other nutritional deficiencies that may also affect fertility

This represents an emerging area where clinical practice may reasonably extend beyond current guideline recommendations, given the low risk of screening, high prevalence of deficiency, and substantial potential benefit demonstrated in recent studies.