人们往往发现农村小孩的智力发育要比城市的小孩差些;生活水平低的要比生活条件好的孩子差些。孕妇素食是一条重要的原因。孕妇长期素食,所生的婴儿由于缺乏维生素 B_(12)往往会患不可逆的脑损害症。这种损害表现在婴儿出生三个月后,会变得感情淡漠,头颈柔软不稳定,并出现舌和腕等不自主运动,严重者可发生巨幼细胞性 People often find that rural children have less intellectual development than urban children; those with a lower standard of living are worse off than those with better living conditions. Pregnant women, vegetarian is an important reason. Pregnant women have long been vegetarian, born babies often suffer from irreversible brain damage due to lack of vitamin B_ (12). This damage is manifested in the baby after three months of birth, will become apathetic, soft and unstable head and neck, and the tongue and wrist involuntary movements, severe cases may occur megaloblastic