A longitudinal study of body iron status during pregnancy and risk of gestational diabetes: findings from a prospective, multiracial cohort

Authors

• S Rawal
• SN Hinkle
• W Bao
• Y Zhu
• J Grewal
• PS Albert
• NL Weir
• MY Tsai
• C Zhang

Abstract

Background: Iron supplementation is recommended for pregnant women. Emerging findings, however, have raised concerns due to significant links between greater iron stores and increased type 2 diabetes risk among non-pregnant individuals. Prospective studies examining iron status in pregnancy and gestational diabetes (GDM) risk are limited and conflicting. Methods: A case-control study of 107 GDM cases and 214 controls (matched 1:2 on age, race/ethnicity, and gestational week of blood draw) was conducted within the prospective NICHD Fetal Growth Studies-Singleton Cohort (2009-2013). Plasma hepcidin, ferritin, and soluble transferrin receptor (sTfR) were measured, and sTfR:ferritin ratio was derived, twice before GDM diagnosis (gestational weeks 10-14 and 15-26), and at weeks 23-31 and 33-39. GDM diagnosis was ascertained from medical records. Adjusted odds ratios (aORs) for GDM were estimated using conditional logistic regression adjusting for demographics, pre-pregnancy body mass index, and other major risk factors. Findings: Hepcidin concentrations during weeks 15-26 were 16% significantly higher among GDM cases than controls (median 6·4 vs. 5·5 ng/ml), and positively associated with GDM risk; aOR (95% confidence interval [CI]) comparing highest vs. lowest quartile was 2·61(1·07-6·36). Ferritin levels were positively associated with GDM risk; aOR(95% CI) comparing the highest vs. lowest quartile was 2·43(1·12-5·28) and 3·95(1·38-11·30) at weeks 10-14 and 15-26, respectively. sTfR:ferritin ratio was inversely related to GDM risk; aOR(95% CI) comparing the highest vs. lowest quartile was 0·33(0·14-0·80) and 0·15(0·05-0·48) at weeks 10-14 and 15-26, respectively. Conclusions: Elevated iron stores may be involved in the development of GDM starting as early as the first trimester.

Scientific Focus Area: Epidemiology

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