The association of elevated serum ferritin concentration in early pregnancy with gestational diabetes mellitus: a prospective observational study

Background/Objectives The results linking body iron stores to the risk of gestational diabetes mellitus (GDM) are conflicting. We aimed to measure the serum ferritin level of women in early pregnancy and evaluate the risk of GDM in a Chinese urban population. Subjects/Methods In total, 851 pregnant women between 10 and 20 weeks of gestation took part in the prospective, observational study conducted. The women were divided into four groups by quartiles of serum ferritin levels (Q1–4). Their blood samples were collected and assayed for several biochemical variables at the beginning of the study, and the women were followed up with a 75-g oral glucose tolerance test at 24–28 weeks of gestation. Results The participants had an average serum ferritin concentration of 65.67 μg/L. GDM prevalence within each serum ferritin quartile was 9.4%, 14.6%, 18.8% and 19.3%, respectively, ( P = 0.016). The odds ratio for GDM in the ferritin Q2–4 was 1.64 (CI: 0.90–2.99), 2.23 (CI: 1.26–3.96) and 2.31 (CI: 1.30–4.10), compared with Q1, respectively. This association persisted after adjusting for potential confounders factors. In addition, in Q4, pregnant women with a pre-pregnancy body mass index ≥24 kg/m 2 , maternal age ≤35 years old or haemoglobin≥ 110 g/L did have an increased risk of developing GDM. Conclusions Elevated serum ferritin concentrations in early gestation are associated with an increased risk of GDM, especially in pregnant women who have a high baseline iron storage status with no anaemia or who are overweight/obese. Individual iron supplementation should be considered to minimize the risk of GDM.