Q: I'm considering pregnancy at the age of 51. What are the health risks—both for me and for the baby?

A: I'm going to answer this question in general, and then get into some specifics about the risks that increase with age.

First, it's important to think about your general health. Many health problems can be affected by pregnancy or, conversely, have an effect on the pregnancy. For example:

  • Do you have high blood pressure, or heart or kidney disease? These may all worsen during pregnancy and may cause your baby to be underweight at birth.

  • Do you have diabetes? If your blood sugar is not controlled during pregnancy, diabetes can increase the risk of miscarriage and birth defects.

  • Were you or your partner born with a heart defect? If so, your children may be at increased risk for similar defects.

  • Are you or your partner affected with a genetic disease such as sickle cell anemia or cystic fibrosis? If so, you may pass it on to your baby. Some people who are healthy can also pass genetic diseases on to their children if they carry the gene for the disease.

Sometimes a preexisting health condition will place a woman at risk for death or serious disability if she gets pregnant. Some women with heart, lung, or autoimmune diseases may be advised not to become pregnant. In other cases, such conditions make it challenging for a woman to tolerate the increased demands that a pregnancy places on the body, such as increased work for the heart and limitations in lung capacity. In these cases, the woman has to limit her activity when pregnant.

Since you are over 50, you will have a higher risk of certain complications that are unique to pregnancy. This is especially true if you have high blood pressure, diabetes, or kidney disease, or you are obese. Two examples are gestational diabetes (high blood sugar in women who are not diabetic before pregnancy) and preeclampsia (high blood pressure, swelling, and protein in the urine, often associated with abnormalities of the liver, kidneys and other organs).

Advancing age can affect many of the risks of pregnancy. As mentioned, older women are at increased risk for preeclampsia and diabetes. Older women are also more likely to have pre-existing health conditions that may affect pregnancy outcome or make them less likely to tolerate the demands pregnancy places on the body. Also, as women age—or, rather, as their ovaries age—their children are at increased risk for having an extra chromosome. The most common of these conditions is Down syndrome, where there is an extra chromosome 21. In 35-year-old women, about 1 in 250 conceptions has an extra chromosome 21. This risk rises to 1 in 100 at age 40, and 1 in 20 at age 45.

Nearly all women who become pregnant after 50 do so with another woman's eggs, using egg donation and in-vitro fertilization (IVF). Conceiving this way generally decreases the risk of genetic conditions such as Down syndrome, since the egg donor is most often younger than the woman who will carry the pregnancy. On the other hand, IVF carries its own set of risks, including a risk of having twins, triplets, or other multiples, which can cause preterm delivery, preeclampsia, and gestational diabetes.

Clearly, there is much to balance here (and we haven't even considered how one's past pregnancy history can affect risk). Each woman (or couple) will evaluate these risks differently. Risks too high or too dangerous for some will seem appropriate to others.

I suggest consultation with an obstetrician, a maternal fetal medicine specialist, and/or an infertility specialist before you get pregnant so you can understand your personal risks.