Background: We aimed to evaluate the prevalence of iron supplementation during pregnancy among participants in the Korean Pregnancy Outcome Study (KPOS) and to determine the effect of iron supplementation on the prevention of anemia and adverse pregnancy outcomes.
<br>Methods: This study prospectively analyzed data collected from KPOS visits 1, 2, and 3 at approximately 12, 24, and 36 gestational weeks. At each visit, the intake of iron and/or multiple micronutrients (MM) supplements was evaluated, and participants who taking iron and/or MM supplements were categorized into the iron supplementation group. Hemoglobin levels were measured at visits 1 and 3. Anemic and normal pregnancy were defined as having hemoglobin levels <11 and ≥11 g/dL, respectively. Adverse pregnancy outcomes included preterm delivery, low birth weight, small for gestational age neonate, low Apgar score, hypertensive disorders of pregnancy, gestational diabetes mellitus. Multiple logistic regression models were performed to assess the independent association.
<br>Results: The prevalence of iron or MM supplementation in the KPOS cohort during the first, second, and third trimester was 37.4%, 92.3% and 91.8%, respectively. Among participants who had anemia during the first trimester, the incidence of low birth weight (LBW) neonates in women with and without iron or MM supplementation in the first trimester was 2.9% and 12.5%, respectively. In addition, among participants who had normal hemoglobin level, iron or MM supplementation during the first trimester was significantly associated with a decreased risk of anemia during the third trimester (6.4% vs. 9.3%, adjusted Odds ratios [aOR]: 0.71, 95% confidence interval [CI]: 0.51–0.90; P = 0.007) and LBW neonates (2.2% vs. 4.3%, aOR: 0.59, 95% CI: 0.39–0.94; P = 0.025).
<br>Conclusion: Iron or MM supplementation during the first trimester may have a positive effect on preventing the occurrence of LBW neonates in women with normal hemoglobin levels.
