Plasma vitamin B12 and methylmalonic acid
In the control group (taking a supplement without vitamin B12), plasma cobalamin was similar at preconception baseline and 1 month after supplementation commencement, then decreased by 0.41 (0.29 to 0.53, Plasma methylmalonic acid, a metabolic indicator of vitamin B12 insufficiency, in the control group increased by 0.29 (0.19 to 0.39, 