A randomized controlled clinical trial to compare the efficacy of Vitamin D vs placebo to reduce high blood sugar during pregnancy

INTERVENTION: Study site is the antenatal clinic of the Colombo North Teaching Hospital, Ragama. Block randomization will be done using a computer generated sequence using a web based application. Block size has been taken as 6. The generated sequence will be concealed with sealed envelope method. Recruitment of participants and the allocation will be done by two different medical officers leading to allocation concealment. Alfacalcidol 0.25 microgram capsule will be given to the intervention arm once a day orally as Vitamin D supplementation for a period of 4 weeks. Folic acid 1 mg tablet will be given once a day orally for the control arm as placebo for a period of 4 weeks. In addition, folic acid 1 mg tablet once day orally will be given to both groups as it is the standard antenatal practice of Sri Lanka (The control arm will receive this folic acid treatment on top of the placebo treatment). During the trial period blood sugar will be routinely monitored and fetal monitoring will be carried out. If a participant needs to be started on insulin according to blood sugar measurements, they will be dropped from the trial and insulin treatment will be initiated. Outcomes will be measured only in participants who still remain within inclusion criteria after completion of the trial. If patients are removed due to adverse effects of Vitamin D it will be specifically reported in the conclusion and will also be reported to the National Medicines Regulatory Authority. CONDITION: Gestational diabetes PRIMARY OUTCOME: The mean difference of blood glucose levels in the two arms before and after the intervention.; ; Blood glucose levels will be measured by fasting blood sugar (FBS) test and 1hour post prandial blood sugar (PPBS) (post breakfast) test; ; SECONDARY OUTCOME: 1. Occurrence of adverse drug effects such as craniofacial abnormalities, and dental abnormalities in infants.; ; 2. Any other allergic reactions to the vitamin D treatment.; ; 3. Side effects to participant due to excessive vitamin D intake such as,; • Kidney stones ; • Confusion or disorientation ; • Muscle weakness ; • Bone pain ; • Poor appetite ; • Extreme thirst ; • Nausea, vomiting, or constipation.; ; ; 4. Reduction in incidence of the following within the first 24 hours from delivery; ; 5. Admissions to Premature Babies Unit (PBU) after delivery; ; 6. Macrosomia; ; 7. Polyhydramnios; ; 8. Shoulder dystocia; ; 9. Neonatal hypoglycemia; ; ; Any difference of occurrence of the following; ; 10. Gestational hypertension during the pregnancy; ; 11. Caesarian section rate; ; 12. Instrumental delivery rates ; ; INCLUSION CRITERIA: 1. Pregnant women 2. Aged 18‐40 years 3. Diagnosed as a Gestational diabetes by 75g Oral Glucose tolerance test 4. On medical nutritional therapy and/or metformin.