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. 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 and excess weight gain during pregnancy appear to modulate the effectiveness of iron supplementation.