The association between serum ferritin levels and the risk of gestational diabetes mellitus：a prospective cohort study

Abstract

Abstract Background The relationship of serum ferritin levels with the risk of gestational diabetes mellitus (GDM) remains unclear. The aim of this study is to investigate the association between serum ferritin levels and its change with the incident of GDM. Methods A prospective cohort study of 10,871 pregnancies from the China Birth Cohort Study were performed. Serum ferritin levels were measured by direct chemiluminescent method in the first and second trimester. Baseline serum ferritin were categorized into five groups by their quintiles in the first trimester. Serum ferritin changes were divided into four subgroups using the trimester-specific median as cut-off points. GDM was determined by a 75g oral glucose tolerance test at 24–28 weeks of gestation. Multivariate modified Poisson regressions were performed to estimate the independent relationship between serum ferritin levels and its change with the incident GDM. Results The median of serum ferritin levels in the first trimester was 57.7 ng/mL, and 13.5% of subjects developed GDM. After multivariate adjustment, the RRs and 95% CIs for incident GDM across baseline serum ferritin quintiles were 1.099 (0.940–1.285), 1.228 (1.055–1.430), 1.186 (1.018–1.383) and 1.179 (1.017–1.367), respectively. Furthermore, subjects with low serum ferritin levels in the first trimester but increased to high level in the second trimester (RR = 1.376,95%CI:1.169–1.612), as well as subjects with consistently high serum ferritin levels in the first and second trimester (RR = 1.351,95%CI:1.185–1.541) had a significantly increased risk of GDM. Conclusions Serum ferritin and its changes were independent risk factors of GDM. These findings underscore the importance of keeping iron metabolism at an appropriate level during early to middle pregnancy to reduce the risk of developing GDM.