Background and aims Central nervous system (CNS) appears in the 3rd week of development, derived from the ectodermal sheet and from the neural plate. The frequency of CNS abnormalities ranges from 0.8 to 1.3/100 live births, and neural tube defects (NTD) are the most common. They are associated with a variety of genetic syndromes, chromosomal abnormalities and a variety of environmental factors.

Methods Retrospective descriptive study by review of medical records of patients diagnosed with CNS malformations in pregnancies controlled on our hospital between 2004–2012.

Results There were 17,759 births, 515 fetuses with birth defects diagnosed prenatally and 114 were CNS defects. In 109 cases an abortion was performed, and 5 live births (acraneo, Dandy Walker, ventriculomegaly, choroid plexus cyst, and a combination). Among the aborted fetuses 49 cases were diagnosed of (NTD), 21 brain defects, 9 midline brain abnormalities, 2 cerebellum defects, and 28 syndromic or multiple malformations. Women with affected fetuses present a mean age of 31.5 years (range 14–44 years), 45 were primiparous. The mean gestational age at the time of abortion was 17 weeks (range 11–29).

Conclusions Of all fetuses aborted with prenatal diagnosis of a congenital defect, CNS abnormalities corresponded to 22.5%.

Women with prenatal diagnosis were not elderly, and most had previous pregnancies without abnormalities.

An important number of CNS malformations are associated with genes or chromosomal syndromes (24%), and the most frequently isolated cases correspond to NTD (42.2%), it believes that this group can be prevented by the intake of preconception folic acid.