在美国,平均每年有2500多名新生儿伴有先天性缺陷,其中最为常见的是脑血管异常和无脑畸形。前者可能导致瘫痪,后者可能导致大脑不完全发育甚至坏死。这种缺陷生成于受孕的最初几个月中,通常早于妊娠反应期。如今,美国健康中心向所有处于生育期的妇女们推荐:每天摄入 In the United States, an average of more than 2,500 newborns each year have congenital defects, the most common of which are cerebrovascular abnormalities and anencephaly. The former may cause paralysis, which may lead to incomplete development or even necrosis of the brain. This defect occurs during the first few months of conception, usually earlier than the pregnancy response period. Today, the U.S. Health Center recommends to all women in their reproductive years: daily intake