Iron deficiency with and without anemia in pregnancy: A scoping review of prevalence and perinatal impact.

BACKGROUND

The prevalence of iron deficiency with anemia and iron deficiency without anemia (IDWA) during pregnancy have not been summarized, and evidence of the direct association of IDWA with adverse perinatal outcomes (APO) are unknown.

OBJECTIVES

To summarize the prevalence of iron deficiency with and without anemia in pregnancy and determine if there is reported evidence of an effect for IDWA on adverse perinatal outcomes (APO).

SEARCH STRATEGY: Literature search was completed using four electronic databases, with no restrictions on date or language.

SELECTION CRITERIA: Selected were observational studies, randomized controlled trials (RCTs), systematic reviews, meta-analyses, narrative reviews on iron deficiency (ID) in pregnancy, published from inception to May 30, 2025.

DATA COLLECTION AND ANALYSIS: Two independent reviewers screened article titles, abstracts, and full texts. The PRISMA guideline for scoping reviews was followed. A narrative summary was performed.

RESULTS

A total of 33 studies were included comprising five RCTs, 27 observational studies, and one narrative summary, involving 84 618 pregnant women. The prevalence of ID varied from 1.2%-71.0%; 1.2%-55.6% (IDA), and 1.6%-71.0% (IDWA). Two studies exclusively reported on IDWA and APO. The first study reported on preterm birth (adjusted odds ratio [aOR] 0.9, 95% confidence interval [CI]: 0.6-1.4), stillbirth (aOR 4.0, 95% CI: 1.0-14.3), low birthweight (aOR 0.6, 95% CI: 0.4-1.0), and small for gestational age (aOR 0.8, 95% CI: 0.5-1.2) in IDWA versus iron replete. The second study reported an adjusted birthweight of 3140 g (95% CI: 3067-3213) in IDWA and 3202 g (95% CI: 3164-3240) in iron replete individuals (P = 0.16).

CONCLUSIONS

Prevalence of ID varied widely, with substantial variability in biomarkers and diagnostic cut-offs used in case definition. There were limited studies reporting on IDWA and its association with APO. Further research is needed to establish an association and to inform early screening and determine whether treating IDWA improves perinatal outcomes.