Vitamin B12 Dose Escalation Trial in Pregnancy

The inclusion criteria for pregnant women are as follows: * Pregnant female * Has an estimated gestational age of 25 to 28 weeks at study initiation * Is between the ages of 18 and 45 years of age * Lives in the study area and does not plan to travel outside of the study area for the duration of the trial * Consents to participate in the trial The exclusion criteria for pregnant women are as follows: * Known multiple pregnancy (e.g. twins, triplets) * Has severe anemia (hemoglobin \<7 g/dL) * Has pre-pregnancy or early pregnancy Body Mass Index ≥ 35 kg/m2 * Has a self-reported pre-pregnancy history of type II diabetes mellitus, hypertension, or hypercholesterolemia. * Has currently diagnosed preeclampsia or eclampsia. * Has currently diagnosed gestational diabetes. * Has currently diagnosed renal, liver, autoimmune, or bleeding disorders. The investigators will also assess all women for clinical signs of liver disease including: jaundice or yellowing of skin/sclera/mucosa, right upper quadrant tenderness or pain. All women will be given a liver function test, regardless of clinical signs of liver disease. The tests include: serum Alanine aminotransferase (ALT) and serum Aspartate aminotransferase (AST). Abnormal liver function is defined as the following in this study for women who the investigators screened during the 2nd trimester (25-26 weeks), ALT below 2 or above 33 U/L, or AST below 3 or above 33 U/L; for women screened during the 3rd trimester (27-28 weeks), ALT bel…