(1041) Compliance and Side Effects of Iron vs. Placebo for Non-Anemic Iron Deficiency in Pregnancy

Non-anemic iron deficiency (NAID) in pregnancy is common and a known risk factor for the development of anemia. As part of a study to examine the effects of iron supplementation on anemia rates, we evaluated the compliance and side effect profile of iron supplementation compared to placebo in pregnant individuals with NAID.

Study Design:

This was a double-blinded, randomized controlled trial at a single academic center from 08/2022 to 03/2024. Patients ≤20 weeks gestation with NAID, defined as low ferritin (< 30 mcg/L) and normal hemoglobin ( >11g/dL) were included. Participants were randomized to receive an iron supplement or placebo pill daily and prenatal care providers were blinded to the treatment arm. Outcomes assessed compliance and side effects in the second and third trimester, based on two telephone surveys. Intention-to-treat analysis included chi-square tests, and t-tests or nonparametric equivalents.

Results:
There were 132 patients with NAID included in the study with 64 in the treatment group and 68 in the control group. At the second trimester survey, there was no significant difference between treatment and control group regarding compliance (n=39, 83.0% VS n=47, 88.7%, p=0.41), observance (mean= 6.4, SD=1.3 vs mean=6.5, SD=1.1, p=0.74) and attrition (n=8, 12.5% VS n=7, 10.3%, p=0.72). At the third trimester survey, there were no significant group difference in compliance (n=26, 61.9% VS n=33, 80.5%, p=0.06), observance (mean= 6.2, SD=1.5 vs mean= 6.2, SD=1.2, p=0.93) and attrition (n=8, 12.5% VS n=9, 13.2%, p=0.91). Participants in both groups reported similar side effects at the second and third trimester (Table 1 and 2) except for significantly higher rates of third trimester vomiting in the treatment group compared to the placebo group (n=5, 14.3% VS n=0, 0%; p=0.02).

Conclusion:
Iron supplementation was generally well tolerated and had similar compliance and attrition rates compared to placebo during the second and third trimesters. Side effects were not significantly different between groups, except for a higher incidence of third trimester vomiting in the iron group.