SUN-632 The Impact of Vitamin D Deficiency on Pregnancy in Type 1 Diabetes

Abstract Vitamin D deficiency during pregnancy may not only impair maternal skeletal preservation and fetal skeletal formation but also influence fetal “imprinting” that may affect chronic disease susceptibility soon after birth as well as later in life. Vitamin D deficiency has been linked to multiple adverse perinatal outcomes in pregnancy including; pre-eclampsia, gestational diabetes, low birth weight, bacterial vaginosis, pre-term delivery and caesarean section. Aim: to assess 25-hydroxy vitamin D (25OHD) concentrations in women with type 1 diabetes (T1DM) during pregnancy, post-delivery and also foetal (cord blood) 25OHD concentrations and to examine relationships between these. The second aim of the study to examine potential relationships between maternal 25OHD and glycosylated haemoglobin (HbA1c) throughout pregnancy. Materials and methods: This was an observational study of 42 pregnant controls without diabetes and 39 pregnant women with T1DM. Maternal serum 25OHD was measured serially throughout the pregnancy and post-delivery. Cord blood 25OHD was measured at delivery. 25OHD was measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). HbA1c was measured serially throughout the pregnancy. Control and T1DM groups were not significantly different in age or number of previous miscarriages. As expected, the T1DM group exhibited significantly higher HbA1c levels, and also had significantly increased incidence of preeclampsia (2 of 42 cases (4,8%) in control group and 5 of 39 cases in T1DM group (12,8%)) (p= 0,03). Delivery gestational age was significantly lower for babies born to mothers with T1DM (39,6±1,4 weeks in control group and 37,6±2,1 in T1DM group (p= 0,001). Vitamin D deficiency, defined as 25OHD levels,25 nmol/L, was apparent in both the control and the T1DM groups across the entire pregnancy. Greater than 90% of pregnant women were classified as insufficient at each time-point, regardless of whether they had T1DM or not. This meant that 10% of this pregnant population were at a sufficient level at some point throughout pregnancy. Similar to maternal vitamin D levels, the neonates had a high incidence of 25OHD deficiency at birth. Also were shown correlations between cord blood and maternal vitamin D. Maternal 25OHD correlated positively with cord 25OHD at all 3 trimesters in the T1DM group. Conclusions: in T1DM pregnancy, low vitamin D levels persist throughout gestation and post-delivery; maternal vitamin D levels exhibit a significant negative relationship with HbA1c levels, supporting a potential role for this vitamin in maintaining glycaemic control; larger studies investigating whether low vitamin D levels are a risk factor for preterm delivery and preeclampsia in women with diabetes are needed.