Iron Supplementation in Non-Anemic Pregnancy and Risk of Developing Gestational Diabetes Mellitus

Abstract

Background: Routine iron supplementation for all pregnant women in order to reduce adverse neonatal outcomes has been a standard practice in developing countries, including Thailand. However, there is evidence that excess iron can affect glucose metabolism and may increase risk of gestational diabetes mellitus (GDM). This study aims to investigate the association of iron supplementation starting from early gestation and the risk of GDM in non-anemic women.

Methods: This retrospective cohort study included non-anemic pregnant Thai women who received their first antenatal care and delivered at Vajira Hospital (Bangkok, Thailand) during January 2008 to December 2009. All pregnant women underwent oral glucose tolerance test during gestational weeks 24 - 28. The proportions of ongoing GDM and birth outcomes were compared between the early oral iron supplementation group (before 16 completed weeks) and the control group (after 16 weeks).

Results: There were 1,935 non-anemic pregnant women, 966 in the early supplement group and 969 in the control group. The early supplement group had significantly higher prevalence of GDM than the control group did (9.7% vs. 5.6%, RR: 1.83; 95% CI: 1.29 - 2.59). No significant differences in maternal anemia, gestational age at birth, or neonatal birth weight were observed between groups.

Conclusions: Early antenatal iron supplementation in non-anemic pregnant women was found to be associated with significantly increased risk of GDM.




J Endocrinol Metab. 2018;8(6):139-143
doi: https://doi.org/10.14740/jem543