Scenario
Mary and John are considering expanding their family, and because their first child—who is 10 years old—has Down syndrome, they are seeking guidance about the likelihood of a future baby being born with the same condition.
The Risk for the Development of Down Syndrome
A person is genetically prone to Down syndrome if they have a third copy of chromosome 21. It affects one in every eight hundred live births. It is associated with intellectual disability, recognizable facial characteristics, and other health problems, such as anomalies of the heart and digestive system. As a mother ages, her probability of giving birth to a child with Down syndrome rises. For example, a 25-year-old woman faces a risk of about 1 in 1,200, a 35-year-old woman has a risk of roughly 1 in 350, and a 45-year-old woman’s risk increases to about 1 in 30 (Stallings et al., 2019).
The Recurrence Risk in a Second Pregnancy.
Since Mary and John already have a child with Down syndrome, there may be a higher chance that they will have more children with the disease. The possibility of recurrence of Down syndrome depends on several factors, including maternal age and whether the child with Down syndrome acquired the disorder from the mother or the father.
If the child with the disorder did not inherit it from the mother, the probability of another baby with Down syndrome is around 1 in 100. The risk is approximately 1 in 2,000 lower if the father causes the child’s problem (Stallings et al., 2019). But most of the time, rather than being inherited, Down syndrome results from spontaneous cell division in the egg or sperm.
Mary and John should speak with a genetic diagnostic or medical professional who can take into consideration their unique problems and health information to identify the specific risk for a second child with Down syndrome. They may also consider prenatal testing, such as chorionic villus sampling or amniocentesis, to determine whether the fetus has Down syndrome. Even though there may be a higher probability of having a child with Down syndrome, many families who already have a child with the disease choose to have additional children to experience both the benefits and challenges of motherhood. With the proper medical care and support, children with Down syndrome may have fulfilling lives.
Reference
Stallings, E. B., Isenburg, J. L., Short, T. D., Heinke, D., Kirby, R. S., Romitti, P. A., & Lupo, P. J. (2019). Population‐based birth defects data in the United States, 2012–2016: A focus on abdominal wall defects. Birth Defects Research, 111(18), 1436-1447. Web.