Many women today are waiting until later in life to have children. In the United States, birth rates for women in their 30s are at the highest levels in three decades. However, an older mother may be at increased risk for miscarriage, birth defects, and pregnancy complications such as twins, high blood pressure, gestational diabetes, and difficult labors. Some studies show that while there may be a greater likelihood of pregnancy complications in older women, their babies may not have more problems than babies of younger women. This is more likely when women receive prenatal care and give birth in a health care facility equipped to care for high-risk mothers and babies.
The risk of chromosomal abnormality increases with maternal age. The chance of having a child affected by Down syndrome increases from about 1 in 1,250 for a woman who conceives at age 25, to about 1 in 100 for a woman who conceives at age 40. It is possible that risks may be higher as many statistics only report live births and do not take into account pregnancies with chromosomal abnormalities that were terminated or ended due to natural pregnancy loss.
In general, 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. It is important to know that most babies with Down syndrome are born to women under the age of 35. This is because women under the age of 35 have more babies than women over 35. The doctor may refer parents to a genetic specialist or genetic counselor who can explain the results of chromosomal tests in detail, including what the recurrence risks may be in another pregnancy and what tests are available to diagnose chromosome problems before a baby is born.
Prenatal testing is available to help diagnose or rule out chromosomal abnormalities and other genetic birth defects. Testing may include blood tests, ultrasound (using sound waves to look at internal structures), chorionic villus sampling (testing the tissues around the fetus), or amniocentesis (withdrawing a sample of the amniotic fluid).
Some studies have shown a higher chance of miscarriage (early pregnancy loss) in older mothers. When considering all women, about half of first trimester miscarriages occur because of a chromosomal abnormality in the fetus. Because these abnormalities increase with maternal age, miscarriage is also more likely. A new test is available that looks at cell-free fetal DNA in the mother's circulation to check for chromosomal abnormalities.
Age 35 is considered advanced maternal age, but the risks increase as a woman ages. If you are pregnant and over the age of 30, talk with your doctor about your individual health and discuss plans for helping you and your developing baby maintain a healthy pregnancy.