Homocysteine and methylmalonic acid as indicators of folate and vitamin B12 deficiency in pregnancy

Deficiency of folate during pregnancy is associated with megaloblastic anaemia. Lower levels of folate and vitamin B-12 have been reported in mothers whose offspring had neural tube defects compared to unaffected controls. Increased methylmalonic acid levels are a sensitive indicator of mild vitamin B-12 deficiency and elevated homocysteine levels denote vitamin B-12 or folate deficiency. We have investigated the relationship between serum concentration of total homocysteine, methylmalonic acid, vitamin B-12 and folate in pregnancy. A significant inverse correlation was found between homocysteine and red cell folate and, to a lesser extent, serum folate. In addition, a significant inverse correlation was found between methylmalonic acid and vitamin B-12, No significant relationship was found between homocysteine and vitamin B-12. The relationship between red cell folate and serum folate and homocysteine may be useful for detecting borderline folate deficiency in pregnancy and indicate pregnancies at risk of neural tube defect. These sensitive assays are useful tools for the further investigation of folate vitamin B-12 and metabolism in normal and abnormal pregnancy.