In today's obstetrics it is essential to know and use very specialized techniques that allow an adequate assessment of fetal development and wellbeing. The basis on which the work of obstetricians, pediatricians and neonatologists has been based, has been the prevention of nosological entities that may affect both pregnant women and newborns.Congenital malformations are the second cause of infant mortality in our country and one of the first causes of neonatal morbidity.Because of its interest in continuing to reduce morbidity and mortality due to this cause, the Cuban National Health System is in a constant process of improvement, guaranteeing the implementation of projects and programs that allow prenatal diagnosis of these entities.Among the main tests currently used to diagnose congenital malformations, especially neural tube defects (NTD), is the dosage of alpha-fetoprotein in maternal serum (AFP-SM), which is unique among other prenatal diagnostic methods in that it can be applied to any pregnancy.