Association of oral iron supplementation with birth outcomes in non-anaemic South Indian pregnant women.

BACKGROUND/OBJECTIVES: Iron in high doses or when given to non-anaemic women may have adverse effects on pregnancy outcomes. This study aimed to estimate the supplemental iron intake in non-anaemic pregnant women attending an urban antenatal care setting in South India and examine the association of supplemental iron intake with birth outcomes.

SUBJECTS/METHODS: A cohort of 1196 non-anaemic pregnant women was studied. Daily supplemental iron intake was calculated as total supplemental iron consumed (mg) during pregnancy divided by the total number of days the supplement was recommended. Association of tertiles of supplemental iron intake with term low birth weight (tLBW), preterm delivery and small for gestational age (SGA) was examined using log-binomial regression, adjusting for maternal age, height, body mass index at recruitment, parity, education and type of delivery.

RESULTS

Mean haemoglobin in trimester 1 was 12.4 ± 0.9 g/dl and mean supplemental iron intake was 37.7 ± 4.0 mg/day. Women in the highest tertile (>39.2 mg/day) of supplemental iron intake had an increased risk of tLBW as compared with the lowest tertile (⩽ 36.6 mg/day) (adjusted risk ratio: 1.89; 95% confidence interval: 1.26, 2.83). Although supplemental iron intake was negatively correlated with gestational age (r=-0.20, P<0.001) and birth weight (r=-0.07, P=0.011), there was no association between preterm delivery or SGA and supplemental iron intake.

CONCLUSIONS

It appears that iron supplementation in non-anaemic pregnant women may not be beneficial, as we have observed the adverse effects with a prescribed dose of 45 mg/day. This may warrant the consideration of an individualized approach for antenatal iron supplementation, especially in non-anaemic women.