Iron supplementation and gestational diabetes in midpregnancy.

OBJECTIVE

Iron supplementation in pregnancy seems beneficial for neonatal/maternal outcomes, but it was associated with diabetes and hypertension in the general population.

STUDY DESIGN

We investigated the association between iron supplementation during midpregnancy and metabolic/hypertensive abnormalities in 500 consecutive gestational diabetes mellitus (GDM) and 500 normoglycemic women.

RESULTS

Iron-supplement users (n = 212/1000) showed significantly higher values of prepregnancy body mass index (BMI), actual BMI, waist circumference, blood pressure, fasting glucose, Homeostasis-Model-Assessment-Insulin-Resistance, and lower high-density lipoprotein-cholesterol than nonusers. The prevalence of GDM (70.8% vs 44.4%), hypertension (25.9% vs 9.8%), metabolic syndrome (25.9% vs 10.4%) was significantly higher in the former with a 2- to 3-fold-increased risk at multiple regression analyses. Most glucose values of the oral glucose tolerance test were significantly higher in iron supplemented women, both in GDM and normoglycemic individuals.

CONCLUSION

Iron supplementation is associated with glucose impairment and hypertension in midpregnancy; its potential harmful effects might be carefully debated regarding its effectiveness.