Hyperhomocysteinemia is related to a decreased blood level of vitamin B12 in the second and third trimester of normal pregnancy.

Hyperhomocysteinemia has been associated with several pregnancy complications. We have investigated the variation of plasma total homocysteine (tHcys) during the 2 last trimesters of normal pregnancy and related it to blood vitamin B12 and folate and to the excretion of the degraded intrinsic factor receptor (IFCR) in urine, in a follow-up study of 15 cases. A significant rise in tHcys was observed between the beginning of the second trimester and the third trimester with respective values (median) 6.