As of 2022, Trisomy 21 is the most common type of trisomy, or a condition where the person has three instead of the normal two copies of one of the chromosomes. Trisomy occurs when abnormal cell division takes place leading to an extra copy of a chromosome. That extra copy of chromosome 21 results in a congenital disorder called Down syndrome, which is characterized by a cluster of specific traits including intellectual disabilities, atypical facial appearance, and a high risk of heart disease. Trisomy 21 changes the way in which a fetus’s brain develops, which accounts for many intellectual disabilities. The United States Centers for Disease Control and Prevention, or CDC, estimates Trisomy 21 occurs approximately once in every 700 human births, averaging about 6,000 live Down syndrome births every year in the US. Down syndrome is a lifelong developmental condition, but there are many resources available to those living with Down syndrome and their families.

On 1 February 1998, David T. Helm, Sara Miranda, and Naomi Angoff Chedd published “Prenatal Diagnosis of Down Syndrome: Mothers’ Reflections on Supports Needed From Diagnosis to Birth,” hereafter “Mothers’ Reflections,” in the journal Mental Retardation. In 2007, Mental Retardation changed its name to Intellectual and Developmental Disabilities. Down syndrome is the result of an extra copy or partial copy of chromosome 21, also known as Trisomy 21. It is characterized by traits such as intellectual disabilities, differing facial features, and a high risk for heart disease. In the study, the authors interviewed ten mothers, all of whom had elected to continue with their pregnancy after a prenatal diagnosis of Down syndrome, about their experiences with health care professionals. The article provides suggestions for health care professionals, such as providing up-to-date materials and unbiased information and avoiding judgmental language, so that when mothers receive a prenatal diagnosis of a developmental disability, they are prepared and supported.