Vitamin B12 Dose Escalation Trial in Pregnancy

Vitamin B12 is a cofactor for 2 enzymes that have essential functions in pregnancy, both for maternal health and for fetal development. However, there is currently limited data regarding the metabolic fate and optimal dose of supplemental vitamin B12 and its relationship to vitamin B12 status in pregnancy. This is a single-blinded, stratified, dose-ranging trial of maternal vitamin B12 supplementation during pregnancy that will be conducted at the Ifakara Health Institute Bagamoyo Clinical Trial Unit in Tanzania. The investigators will enroll 40 pregnant women (gestational age 25-28 weeks) and 10 non-pregnant women (comparison group). Participants will be blinded to dosing (2.6, 10, and 50 µg) and supplementation will be given for four weeks. With this trial, the investigators aim to enhance our understanding of vitamin B12 bioavailability during pregnancy in people with sufficient and insufficient baseline B12 status, identify priority dose regimens of vitamin B12 in pregnancy for investigation in later phase clinical trials to be conducted in populations where vitamin B12 insufficiency or deficiency is common, and identify biomarkers of vitamin B12 intake appropriate for pregnancy.