The U.S. Preventive Services Task Force announced, in a recommendation on Sept. 7, that it is unsure whether pregnant women who are asymptomatic for iron deficiency anemia should be screened for this condition or take iron supplements.
The recommendation is an update to the 2006 USPSTF recommendation, which also expressed uncertainty on whether iron supplementation is beneficial to pregnant women.
“Both the 2006 and the current recommendation statements found insufficient evidence to determine the balance of the benefits and harms of iron supplementation during pregnancy,” Dr. Albert L. Siu wrote on behalf of members of the USPSTF.
The 2006 recommendation differed from the current one in that it had advocated for routine screening for iron deficiency anemia in pregnant women.
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“In its review of the evidence to update the 2006 recommendation, the USPSTF found no good- or fair-quality studies on the benefits or harms of screening that would be applicable to the current U.S. population of pregnant women,” according to the task force recommendation statement published in the Annals of Internal Medicine.
The USPSTF based the updated recommendation on a systematic evidence review, which focused on whether pregnant women and adolescents’ use of oral iron supplementation or treatment was associated with changes in iron status and improvement in maternal and infant health outcomes. It reviewed “studies conducted in settings similar to the United States in rates of malnutrition, hemoparasite burden, and general socioeconomic status.”
The USPSTF’s review included 12 “good- or fair-quality randomized controlled trials,” which evaluated the effects of iron supplementation on various maternal hematologic indexes, including hemoglobin level, serum ferritin level, anemia, iron deficiency, and iron deficiency anemia.
Eight of the studies reported maternal hemoglobin levels at term or delivery, with six of the studies having reported a significantly higher mean hemoglobin level in the supplemented groups than in the control groups (122-139 g/L vs. 115-128 g/L, respectively). Seven studies reported serum ferritin levels at term or delivery, with five of these having reported a significantly higher ferritin level in the supplemented groups, compared with the control groups (12.0-30.0 mcg/L vs. 6.2-24.9 mcg/L, respectively).
“Although adequate evidence shows that [iron] supplementation increases hemoglobin and ferritin levels, the evidence is unclear on whether this increase leads to an improvement in maternal and fetal outcomes. In most of these studies, the supplemented groups had higher mean hemoglobin levels than the nonsupplemented groups; however, both groups reported values within normal limits,” the USPSTF wrote.
Research on the harmful effects of iron supplementation in pregnant women better addressed the USPSTF’s questions; 10 of the trials showed that the harms of iron supplementation during pregnancy were “small to none,” with most of the harms reported having been nausea, constipation, and diarrhea.
While the USPSTF found adequate evidence about the lack of harm from iron supplementation, it failed to find adequate evidence on the benefits of supplementation.
“Reported benefits of supplementation were limited to intermediate outcomes (maternal hematologic indexes), and evidence on the benefits of supplementation on maternal and infant health outcomes was inadequate because of inconsistent results and underpowered studies,” the USPSTF wrote.
The group found less research on the outcomes of screening for iron deficiency anemia in asymptomatic pregnant women and adolescents. “No good- or fair quality studies were found that evaluated the benefits or harms of screening in this population,” according to the recommendation.
The USPSTF concluded that the “current evidence is insufficient to assess the balance of benefits and harms of screening for iron deficiency anemia in pregnant women … [and] of routine iron supplementation for pregnant women to prevent adverse maternal health and birth outcomes.”
Read the full recommendation in Annals of Internal Medicine (doi: 10.7326/M15-1707).