What are the chances of a woman having a baby with down syndrome?

ACOG charts show the. risk of having a fetus with a Trisomy 21, Down Syndrome at prenatal diagnosis vs. the risk of having a live-born infant with DS because ~ 25% are lost. If there is no family history or prior infant with DS, at age 42 at delivery, the risk is 1/63; risk at 16 weeks' gestation is 1/50 - 1/55. Risk of any chromosomal disorder at term is 1/42. If 43 at term, DS risk is 1/49; of any trisomy, 1/33. .