High Dose Cholecalciferol to Reduce the Incidence of Gestational Diabetes in High Risk Pregnant Women

Inclusion Criteria: 1. Women who are currently pregnant and receiving prenatal care at the Women's Health Specialists Clinic (University of Minnesota Physicians) from either MD/DO or CNM providers 2. Subject established prenatal care no later than the completed 12th week of gestation (12 6/7 weeks) 3. Subject possesses as least one of the following characteristics: 1. BMI greater than or equal to 30 kg/m2 2. History of gestational diabetes in a prior pregnancy 3. History of infant with birth weight of 4500g or greater 4. Subject is capable of giving informed consent Exclusion Criteria: 1. Age less than 18 years 2. Multiple gestation pregnancies (twins, triplets or greater multiples) 3. Vitamin D deficiency (defined as less than 20 ng/mL) 4. Preexisting diabetes mellitus defined as either: 1. pre-existing diagnosis prior to current pregnancy 2. failure of three-hour glucose tolerance test in first trimester of pregnancy