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How Parents' Age Affects Baby's Genetic Health: What the Numbers Show

NNova editorial team · 6 min read

As maternal age rises, the chance of chromosomal conditions such as Down syndrome increases, and paternal age after about 40 is linked to a small rise in new gene changes. Most pregnancies at older ages still result in healthy babies, and your OB-GYN or genetic counselor can review your personal risk.

Why age can matter

Age does not change a person's ability to love or care for a child, but it can affect the chance of certain genetic changes in eggs and sperm. As a person ages, the chance of an error when eggs divide rises, which can lead to an extra or missing chromosome. Sperm can also develop new gene changes over time. That is one reason age is included in prenatal screening discussions.

What the statistics show

  • The chance of chromosomal conditions, such as trisomy 21 (Down syndrome), rises gradually with maternal age and is higher after 35 and higher again after 40.
  • Even at older ages, most pregnancies result in healthy babies. The chance of a chromosomal condition is still well below 50 percent at most ages.
  • Paternal age over about 40 is linked to a small increase in new gene changes. The effect is generally smaller than the effect of maternal age.
  • Family history, previous pregnancy losses, and screening results often tell your care team more than age alone.

Screening options in the US

ACOG recommends that all pregnant people be offered prenatal screening, regardless of age. Options include cell-free DNA screening (also called NIPT), which uses a blood sample from the mother in the first or second trimester, and first-trimester ultrasound and blood tests. Diagnostic tests such as CVS or amniocentesis can confirm results but carry a small risk of miscarriage. Many providers recommend discussing these choices early so you have time to decide.

Age alone is not a diagnosis. Your care team usually looks at ultrasound findings, blood screening results, your health history, and your family history together. A genetic counselor can help you understand what the results mean for you.

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General information only; it does not replace advice from your doctor or midwife.