Chromosomal alterations are one of the main causes of perinatal death and their early diagnosis allows for specialized prenatal care, with follow-up in tertiary services and a psychological evaluation in order to guide the couple regarding the severity of the findings and the future of the pregnancy.

Over the last few decades, strategies to identify high-risk groups for chromosomal alterations have been based on maternal factors (maternal age and history of genetic alterations in previous pregnancies), ultrasound markers of the first and/or second trimester of pregnancy, and biochemical tests performed in the second trimester (estriol, hCG and alpha-fetoprotein) or in the first trimester (free fraction of β-hCG and pregnancy-associated plasma protein A – PAPP-A) in combination with ultrasound performed between 11 and 14 weeks.

New methods have emerged in recent years that aim to improve the screening and diagnosis of chromosomal alterations. This includes screening techniques through the search for free fetal DNA in maternal blood. Although not all of them are available to the population in the public health system, it is important that obstetricians are aware of these techniques and their clinical applicability, as all efforts must be made to improve screening, diagnosis and care for pregnant women in Brazil.