Baseline iron and low-grade inflammation modulate the effectiveness of iron supplementation: evidence from follow-up of pregnant Sri Lankan women

Purpose We evaluated the effectiveness of iron supplementation in relation to baseline iron and inflammatory status of pregnant women and their offspring in Sri Lanka. Methods Apparently healthy women aged 18–36 years at < 12 weeks of gestation prior to receiving any supplementation were randomly recruited at the antenatal clinics. They received 60 mg of elemental iron in combined iron–folic acid pills from 12 weeks of gestation until delivery via the National Maternal Supplementation Programme. Serum ferritins (SF), hemoglobin and high-sensitive C-reactive protein (hs-CRP) were assessed. The women were grouped as iron sufficient-inflammation (+), iron sufficient-inflammation (−), iron deficient-inflammation (+) and iron deficient-inflammation (−) based on their baseline iron stores and low-grade inflammation (hs-CRP > 5 < 10 mg/L) at baseline and late pregnancy. Results Despite supplementation, SF in the iron sufficient-inflammation (+) women reduced significantly ( p = 0.037) to deficiency state (SF < 30 µg/L) at mid-pregnancy. Whereas no significant changes were noted in the SF in iron sufficient-inflammation (−) women ( p > 0.05). They maintained their stores at sufficient state until delivery. The cord SF was higher ( p < 0.001) in iron sufficient-inflammation (−) than the inflammation (+) women. 96.4% of the iron deficient women remained deficient until delivery regardless of their inflammatory state. Low-grade inflammation was higher ( p < 0.001) in women with baseline BMI > 25 kg/m 2 . Whereas inflammation at late pregnancy was higher ( p < 0.001) in women who gained weight in excess of the recommended, regardless of their baseline BMI. Conclusion Iron status prior to supplementation and low-grade inflammation associated with BMI > 25 kg/m 2 and excess weight gain during pregnancy appear to modulate the effectiveness of iron supplementation.