Congenital anomalies are an important diagnostic group in the perinatal healthcare. Only some of these anomalies have an individual cause (complex anomalies accompanying chromosomal aberrations, congenital anomalies with monogenic inheritance, typical anomalies caused by strong teratogens etc.). The majority of cases of congenital anomalies is caused by multiple and complex factors that are hard to identify. Therefore – the so called primary prevention of congenital anomalies becomes much more important during last years. Primary prevention of congenital anomalies itself is composed of various guidelines and recommendations that should prevent the formation of the anomaly. Specific role in the primary prevention has the folic acid supplementation that is world-wide recommended as the prevention of neural tube defects.