Salakos E, Rabeony T, Courbebaisse M, et al. - Researchers examined the risk of gestational diabetes mellitus (GDM), one of the most frequent medical complications during pregnancy, according to vitamin D status during the first trimester. In this nested case–control study from a multicenter prospective observational cohort of pregnant women assessed for 25-hydroxyvitamin D levels (25OHD), they matched 250 women with GDM (cases) to 941 women without GDM (controls) for parity, age, body mass index before pregnancy, the season of conception, and phototype. Per findings, there appeared no linear relationship between GDM and 25OHD levels in the first trimester of pregnancy as no continuous decrease in GDM risk occurs with increase in 25OHD concentrations. Most probably, findings indicate that there is no correlation between 25OHD levels and GDM risk.