Objective: 1. To examine relationships between 25-hydroxy vitamin D (25OHD) in women with type 1 diabetes (T1DM) during pregnancy, post-delivery and in cord blood. 2. To investigate interactions between maternal body mass index (BMI) and foetal vitamin D status. 3. To examine relationships between maternal 25OHD and glycosylated haemoglobin (HbA1c).
Methodology: An observational study of 52 pregnant controls without diabetes and 65 pregnant women with T1DM in a university teaching hospital. 25OHD was measured by liquid chromatography tandem mass spectrometry.
Results: Vitamin D deficiency (25OHD <25nmol/L) was apparent in control and T1DM women in all 3 trimesters. All cord blood 25OHD were <50nmol/L. Maternal 25OHD correlated positively with cord 25OHD at all 3 trimesters in the T1DM group (p=0.02; p<0.001; p<0.001). Cord 25OHD was significantly lower for T1D women classified as obese vs. normal weight at booking [normal weight BMI <25kg/m(2) vs. obese BMI〉30kg/m(2) (nmol/L±SD); 19.93±11.15 vs. 13.73±4.74, p=0.026]. In the T1DM group, HbA1c at booking was significantly negatively correlated with maternal 25OHD at all 3 trimesters (p=0.004; p=0.001; p=0.05).
Conclusion: In T1DM pregnancy, low vitamin D levels persist throughout gestation and post-delivery. Cord blood vitamin D levels correlate with those of the mother, and are significantly lower in obese vs normal weight women. Maternal vitamin D levels exhibit a significant negative relationship with HbA1c, supporting a potential role for this vitamin in maintaining glycaemic control.
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