Many women wait until later in life to have children. In the U.S., birth rates for women in their 30s are at the highest levels in four decades. But an older mother may be at increased risk for things, such as:

• Miscarriage
• Birth defects
• Twins
• High blood pressure
• Preeclampsia
• Gestational diabetes
• Difficult labor

Some studies show that while there is a higher risk of pregnancy problems in older women, their babies may not have more problems than babies of younger women. This is more likely when women get prenatal care and give birth in a healthcare facility ready to care for high-risk mothers and babies.

The risk for chromosome problems increases with the mother's age. The chance of having a child with Down syndrome increases over time. The risk is about 1 in 1,250 for a woman who conceives at age 20. It increases to about 1 in 86 for a woman who conceives at age 40. The risks may be higher. This is because many statistics only report live births. They don't note pregnancies with chromosome problems that ended due to pregnancy loss.

After having one child with Down syndrome, the chance of having another baby with Down syndrome is higher. After age 40, the recurrence risk for Down syndrome is based on the age of the mother at delivery. Most babies with Down syndrome are born to women younger than 35. This is because women under age 35 have more babies than women over 35.

Some studies have shown a higher chance of miscarriage (early pregnancy loss) in older mothers. For all women, about half of first trimester miscarriages happen because of a chromosome problem in the baby. The risk of chromosome problems increase with the mother's age. So miscarriage is also more likely.

If you're pregnant and over age 35, talk with your doctor about your health. Discuss plans for helping you and your baby have a healthy pregnancy.

Your doctor may refer you to a genetic specialist or genetic counselor. They can explain the results of chromosome tests in detail. This includes what the risks may be in another pregnancy and what tests can diagnose chromosome problems before a baby is born.

Prenatal testing can help diagnose or rule out chromosome problems and other genetic birth defects. Testing may include:

• Blood tests
• Ultrasound. This imaging test uses sound waves to look at organs and other tissues in the baby.
• Chorionic villus sampling (CVS). This test is done on a sample of the tissues around the baby.
• Amniocentesis. This is a test done on a sample of the amniotic fluid.
• Cell-free fetal DNA. This test checks the mother's blood for chromosome problems.