Maternal serum 25-hydroxyvitamin D levels at 11+0-13+6 weeks in pregnant women with diabetes mellitus and in those with macrosomic neonates

Objective To investigate whether maternal serum levels of 25-hydroxyvitamin D [25(OH)D] in the first trimester are altered in pregnant women with pre-existing type 2 diabetes, women who subsequently develop gestational diabetes mellitus (GDM) and women who deliver large for gestational age (LGA) neonates compared with normoglycaemic pregnant women who deliver an appropriate for gestational age (AGA) neonate. Design Case control study. Setting Antenatal clinic. Population Singleton pregnancies at 10(+0)-13(+6) weeks, including 50 women with type 2 diabetes, 100 women who subsequently developed GDM, 50 nondiabetic women who subsequently delivered LGA neonates and 1000 nondiabetic controls who delivered AGA neonates. Methods Maternal serum total 25(OH)D levels were measured in the four groups of pregnancies. Multiple regression analysis in the controls was used to identify factors among maternal characteristics with a significant contribution to the levels of serum 25(OH)D, so that the values in all cases were expressed as a multiple of the median (MoM) in the controls. Main outcome measures Comparison of MoM 25(OH)D in the four groups. Results In controls, significant independent contributions to the serum level of 25(OH)D were provided by maternal age, body mass index, smoking status, racial origin and season of sampling. The median and interquartile range (IQR) of serum 25(OH)D in the type 2 diabetes group (1.01; IQR, 0.68-1.47 MoM), GDM group (0.93; IQR, 0.67-1.23 MoM) and LGA group (0.97; IQR, 0.67-1.25 MoM) were not significantly different from those in the controls (0.99; IQR, 0.71-1.33 MoM) (overall P = 0.643). Conclusions The first-trimester maternal serum level of 25(OH)D is not altered in women with type 2 diabetes, those who develop GDM or those who deliver LGA neonates.