Key highlights in this article:
- The USPSTF concluded that there is insufficient evidence to assess the benefits and harms of screening for iron deficiency and iron deficiency anemia in pregnant persons.
- The Task Force also found insufficient evidence to recommend routine iron supplementation during pregnancy to prevent maternal and infant adverse health outcomes.
- Clinicians are advised to use their clinical judgment regarding screening and supplementation for iron deficiency during pregnancy due to the lack of clear evidence.
Background and statement
In a new statement, the US Preventive Services Task Force (USPSTF) announced that because of insufficient evidence, it was unable to assess the balance of benefits and harms of screening for iron deficiency and iron deficiency anemia in pregnant persons. The USPSTF statement, published in JAMA, also concluded that current evidence is insufficient to assess benefits and harms of routine iron deficiency and iron deficiency anemia supplementation in pregnant persons to prevent maternal and infant adverse health outcomes.1
The Task Force is an independent, volunteer panel of national experts in disease prevention and evidence-based medicine, according to the USPSTF website.2
According to the statement, iron deficiency is the leading cause of anemia amid pregnancy, with an estimated 5% of pregnant persons having iron deficiency anemia. Survey data from 1999 to 2006 demonstrated an overall estimated prevalence during pregnancy near 18%, with increases across the 3 trimesters of pregnancy1:
- First trimester - 6.9%
- Second trimester - 14.3%
- Third trimester - 28.4%
Iron, necessary for hemoglobin production, is also needed for the production of additional proteins that are vital to various metabolic pathways.
"Screening for iron deficiency and iron deficiency anemia often includes measurement of hematologic indices level or hematocrit as proxies of iron deficiency anemia), and an abnormal screening test result may be followed by treatment with iron therapy," statement authors said. "To establish the presence of iron deficiency or iron deficiency anemia, levels of iron biomarkers (eg, ferritin) may be measured, although there is no consensus on the exact ferritin level that is indicative of iron deficiency."1
To evaluate evidence on the benefits and harms of screening and supplementation for iron deficiency with and without anemia on maternal and infant health outcomes, the USPSTF commissioned a systematic review in asymptomatic pregnant adolescents and adults.1
The statement related to insufficient evidence to recommend for or against screening or supplementation during pregnancy is consistent with the 2015 recommendation statement. The Task Force recommends, based on the lack of evidence, that clinicians "should use their clinical judgment regarding whether to screen for iron deficiency and iron deficiency anemia and whether to provide routine iron supplementation during pregnancy."1
Potential harms
Screening approaches to identify asymptomatic pregnant persons with iron deficiency are unlikely to cause serious harms, noted the Task Force, though it recognized that evidence is limited. Evidence that was reviewed for the statement did not report risk of iron overload. Iron supplementation or treatment adverse effects can include gastrointestinal tract symptoms such as nausea, constipation, abdominal pain, and vomiting, stated the authors.1
Benefits
The review found "no evidence on the benefits of screening and treatment for screen-detected iron deficiency and iron deficiency anemia during pregnancy on maternal and infant health outcomes."
The review of a single observational study (n = 20,690) addressed the association between change in maternal iron status in pregnant persons with iron deficiency with or without anemia and clinical outcomes. In pregnant persons who responded to treatment—defined as persons with a normal hemoglobin value at delivery who reported taking iron supplementation—therapy was associated with a reduction in the odds of preclampsia (adjusted odds ratio, 0.75 [95% CI, 0.61-0.91) and preterm birth (adjusted odds ratrio, 0.59 [95% CI, 0.47-0.72]) versus persons without anemia.1
"Nonresponse to therapy or untreated anemia was also associated with increased risk of preterm birth and preeclampsia (adjusted OR, 1.44 [95% CI, 1.16-1.76] and 1.45 [95% CI, 1.26-1.67], respectively) compared with no anemia," the statement said.1
In a review of 16 studies that compared the effects of routine iron supplementation with no supplementation to determine maternal or infant health outcomes, evidence was "limited, inconsistent, or without clear benefit," stated the authors. Evidence was limited or demonstrated no benefit in 6 supplemental trials evaluating infant health outcomes, as 5 trials reported no association between supplementation and infant mortality. After a post-hoc analysis, 1 trial did report a statistically significant difference in rates of neonatal deaths in the supplementation group compared to control (1.1% vs 2.0%; RR, 0.53 [95% CI, 0.29-0.97]).1
Other recommendations
The Task Force noted throughout the statement that this recommendation applies to asymptomatic pregnant adolescents and adults, and not to pregnant persons who are severely malnourished, have symptoms of iron deficiency or iron deficiency anemia, or for those who have specific hematologic conditions—such as sickle cell disease—or nutritional deficiencies that may increase need for iron.1
Separate recommendations have been previously issued on screening for iron deficiency anemia in children aged 6 to 24 months of age (2015), which also stated "that the current evidence is insufficient to assess the balance of benefits and harms of screening for iron deficiency anemia in children ages 6 to 24 months."1,3
References:
- US Preventive Services Task Force. Screening and Supplementation for Iron Deficiency and Iron Deficiency Anemia During Pregnancy: US Preventive Services Task Force Recommendation Statement. JAMA. Published online August 20, 2024. doi:10.1001/jama.2024.15196
- US Preventive Services Task Force. Accessed August 20, 2024. https://www.uspreventiveservicestaskforce.org/uspstf/
- Siu AL; US Preventive Services Task Force. Screening for iron deficiency anemia in young children: US Preventive Services Task Force recommendation statement. Pediatrics. 2015;136(4):746-752. doi:10.1542/peds.2015-2567
