**1. Epidemiology. Incidence and risk factors for cardiac abnormalities**

Congenital heart defects (CHD) are the most frequent congenital malformations (5–12 per 1000 live births), the costliest hospital admissions for structural defects and represent the leading cause of infant general and malformations related mortality (42%) [1, 2]. Prenatal CHD detection allows proper counseling, provides the options of pregnancy termination [3], in utero treatments (antiarrhythmics, valvuloplasties, etc.) [4–7] and allows for delivery planning in a referral center [8–11].

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

CHD etiology includes many genetic, environmental and teratogenic factors [12–16], but 90% of heart malformations have no identified cause. Conversely, the risk may be reduced with periconceptionally folic acid intake [17].
