"New Study Questions Routine Iron Supplementation During Pregnancy, Urges Individualized Care"

A new study from Oregon Health & Science University, supported by the Agency for Healthcare Research and Quality at the U.S. Department of Health and Human Services, reveals that while routine prenatal iron supplementation reduces the incidence of iron deficiency and related anaemia during pregnancy, it does not significantly impact maternal or infant health outcomes, such as maternal hypertension.

This suggests that for most pregnancies, additional iron supplementation — which can cause nausea and constipation — may not be necessary.

Published today in JAMA Network Open, the study will inform updated recommendations by the U.S. Preventive Services Task Force, a group supported by the federal Agency for Healthcare Research and Quality that makes evidence-based recommendations on clinical preventive services.

“There’s a lot of marketing aimed at pregnant people for various vitamins and supplements, which can be overwhelming,” said Amy G. Cantor, M.D., M.P.H., a professor in the OHSU School of Medicine and the study’s lead author. “It’s best to keep it simple: If you don’t have any risk factors identified by your clinician, then a standard prenatal vitamin should suffice for a healthy pregnancy.”

Iron deficiency is the most common cause of anemia during pregnancy, a condition where there are lower levels of healthy red blood cells to carry oxygen throughout the body, sometimes resulting in fatigue or shortness of breath. In the U.S., nearly 18% of pregnant individuals are iron deficient, with 5% developing iron-deficiency anemia. The condition is more prevalent in certain populations, including Black and Mexican American individuals, and those with lower income levels who may lack access to iron-rich foods.

Screening for iron deficiency during pregnancy is common and can lead to early treatment, though the evidence connecting iron levels to perinatal health outcomes is limited.

“Our clinical question was whether iron supplementation improves maternal and infant health outcomes, and the evidence was quite limited,” Cantor said. “We hope clinicians will use this information to enhance discussions with patients about symptoms and health history, allowing for more tailored treatment.”

In 2015, the U.S. Preventive Services Task Force (USPSTF) found insufficient evidence to assess the benefits and harms of routine screening and supplementation for iron deficiency during pregnancy. This new OHSU study aims to inform updated USPSTF recommendations on routine screening and supplementation.

The systematic review analyzed 17 trials on maternal iron supplementation, finding no statistically significant differences in health outcomes, such as maternal quality of life, rates of gestational diabetes, maternal haemorrhage, hypertensive disorders, caesarean delivery, and infant low birth weight, when compared with a placebo or no supplementation.

Although iron supplementation has few harms, it can cause short-lived gastrointestinal side effects like nausea or constipation, which can be particularly uncomfortable during pregnancy.

Given the limited impact on maternal and infant health outcomes, clinicians can use these findings to help decide whether pregnant patients should take iron supplements in addition to their prenatal vitamins, based on individual history and symptoms. Iron is often included in prenatal vitamins but can also be obtained from foods like lean meat, seafood, spinach, and certain legumes.

Cantor emphasizes that these findings apply to asymptomatic, average-risk pregnant individuals and not to those with severe iron deficiency. She also calls for further research to explore the relationship between changes in maternal iron levels and health outcomes.

“This study reinforces the need for individualized prenatal care, as each patient’s experience with pregnancy is unique,” Cantor said. “Prenatal care shouldn’t be one-size-fits-all, and we hope this review encourages more personalized discussions between patients and providers about health during pregnancy.”