The chances of having a baby with chromosomal abnormalities can vary depending on various factors, including maternal age, paternal age, family history, and individual genetic factors. For instance, the risk of chromosomal abnormalities, such as Down syndrome, increases with maternal age. On average, for a woman in her 20s, the risk of having a baby with Down syndrome is approximately 1 in 1,500. However, by the age of 35, the risk increases to about 1 in 350, and by the age of 45, the risk is about 1 in 30. It's important to note that these statistics are general estimates, and the individual risk can vary. Genetic counseling and prenatal testing options can help assess the specific risk factors and provide more accurate information based on individual circumstances.