Prenatal Iron Supplementation Reduces Maternal Anemia, Iron Deficiency, and Iron Deficiency Anemia in a Randomized Clinical Trial in Rural China, but Iron Deficiency Remains Widespread in Mothers and Neonates.

This was a 1:1 randomized, placebo-controlled trial in pregnant women with uncomplicated singleton pregnancies in rural Sanhe County, Hebei Province, China. Women were enrolled at their first prenatal visit before 20 weeks' gestation and followed through delivery; in the iron/folate arm, 823 women were randomized and 814 contributed outcome data.

Participants in the active arm received one oral capsule daily from enrollment to delivery containing 300 mg ferrous sulfate (60 mg elemental iron) plus 0.40 mg folate. The comparator received matched placebo capsules plus 0.40 mg folate.

Prenatal iron supplementation improved maternal iron status and reduced maternal anemia, iron deficiency, and iron deficiency anemia, but it did not significantly improve cord blood iron measures or neonatal iron status overall. In the iron/folate group versus placebo/folate, maternal anemia at or near term was 13.4% vs 25.1% (RR 0.53; 95% CI 0.43, 0.66), maternal Hb was higher by 5.56 g/L, and postpartum anemia was reduced (RR 0.71; 95% CI 0.66, 0.78). Maternal iron deficiency and iron deficiency anemia were also lower (for example, IDA by serum ferritin: RR 0.49; 95% CI 0.38, 0.62), yet more than 45% of neonates had iron deficiency at birth in both groups. Cord blood ferritin increased with greater maternal capsule consumption (b per 10 capsules = 2.60, P < 0.05), suggesting adherence mattered for fetal iron stores. Serious adverse outcomes were uncommon and not significantly different between groups.

Neonatal and cord-blood analyses were limited by substantial missing data, and adherence data were incomplete for later pregnancy, with only 46.4% of second-trimester-to-delivery data available. The trial was conducted in rural Hebei among women with uncomplicated singleton pregnancies, which limits generalizability, and the intervention did not translate into a clear neonatal iron benefit overall.