A major review article [31] of 122 observational studies and 1 randomized trial found that low maternal or cord blood B12 was associated with gestational diabetes (1 study), neural tube defects (9 studies), spontaneous abortions (2 studies), low birth weight/IUGR/small for gestational age (3 studies), congenital heart defects (4 studies), poorer infant memory (1 study), excessive crying (1 study), infant/child insulin resistance (3 studies). This evidence concerns the gene INS and neural tube defect.