Causal effect of maternal vitamin D levels and body mass index on pregnancy-related outcomes

We aim to improve the understanding on whether low maternal vitamin D levels and high maternal body mass index (BMI) can contribute to developing adverse outcomes during and after pregnancy, such as gestational diabetes, miscarriages, stillbirth, need for caesarean, low birth weight and longer hospital stays after delivery. Investigating the influence of maternal BMI and vitamin D levels on pregnancy-related adverse outcomes fits with the central aim of UK Biobank to improve prevention and treatment of diseases. For this study, we will use data on BMI, vitamin D levels, genetics, and obstetric-related outcomes in all women that have ever being pregnant. We will compare women with different genetic makeups related to vitamin D and BMI using a technique named Mendelian randomisation to assess whether low maternal vitamin D levels or high maternal BMI are likely to increase the risk of developing adverse pregnancy-related events. Data will be requested for females only (n < 273,000)