USPSTF's Latest Statement Highlights Gaps in Evidence for Iron Deficiency Screening During Pregnancy

The US Preventive Services Task Force Recommendation statement is published online in JAMA.

Iron deficiency remains a prominent issue in pregnancy, being the leading cause of anemia among this population. Historical data from surveys conducted between 1999 and 2006 reveals that approximately 18% of pregnant individuals experience iron deficiency, with prevalence rates increasing as pregnancy progresses through its three trimesters. Additionally, about 5% of pregnant individuals are affected by iron deficiency anemia.

Despite the recognized prevalence and potential impact of iron deficiency, the USPSTF's current recommendation underscores a lack of clear evidence on the effectiveness of routine screening and supplementation in preventing adverse maternal and infant health outcomes. This recommendation aligns with the Task Force's stance from 2015, reflecting the ongoing uncertainty in the field.

The USPSTF routinely assesses preventive care services and makes recommendations based on available evidence. Their latest statement suggests that while iron deficiency is a significant concern, the existing data does not sufficiently support a blanket approach to screening and supplementation for all pregnant individuals.

The USPSTF commissioned a systematic review to evaluate the evidence on the benefits and harms of screening and supplementation for iron deficiency with and without anemia on maternal and infant health outcomes in asymptomatic pregnant persons.

This recommendation applies specifically to asymptomatic pregnant adolescents and adults and does not extend to those with severe malnutrition, symptoms of iron deficiency, iron deficiency anemia, or specific hematologic conditions such as sickle cell anemia.

Iron is crucial for producing hemoglobin, which transports oxygen throughout the body, and for various metabolic functions. Iron deficiency, which can lead to iron deficiency anemia, is a common issue during pregnancy due to increased iron demands. Despite its prevalence, the exact definition of iron deficiency remains debated, and screening often involves measuring hematologic indices like hemoglobin levels. However, there is no consensus on the precise ferritin levels indicative of deficiency.

The USPSTF's recommendation highlights a significant gap in evidence concerning the effectiveness of routine iron screening and supplementation. Although the prevalence of iron deficiency anemia increases throughout pregnancy, and certain groups, such as Black and Mexican American pregnant individuals are disproportionately affected, there is no universally accepted method to assess risk or effectiveness. Current practices in screening and supplementation vary, with some guidelines differing significantly. A recent survey showed that over half of pregnant participants in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) underwent hemoglobin testing during their first trimester. Additionally, data from NHANES indicated that a substantial portion of pregnant individuals use iron supplements.

The USPSTF’s review identified limited evidence on the benefits of screening asymptomatic pregnant individuals for iron deficiency or anemia. Potential harms from screening are minimal, but common side effects of iron supplementation include gastrointestinal issues such as nausea and constipation. There is also evidence of racial and ethnic disparities in screening and supplementation rates, highlighting a need for more equitable practices.

In conclusion, while iron deficiency remains a critical concern, the USPSTF's latest recommendation underscores the need for more research to clarify the best practices for screening and supplementation during pregnancy.

Reference:

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