The increased risks in these pregnancies include miscarriage, conceiving twins, fetal genetic abnormality, some birth defects, developing diabetes during pregnancy, preeclampsia (which is high blood pressure in pregnancy), stillbirth, and cesarean delivery. Some of these complications may result in preterm birth. Benefits include that older women tend to be more emotionally mature and financially stable than when they were younger.
The reported rates of miscarriage increase over the age of 35 and further increase in women 40 years of age or older. It is currently much more common to see women having their first pregnancy over the age of 35 and this rate has continued to rise in the United States since 1990. The complication that many women who are considering becoming pregnant encounter is an increased risk of having a fetus with a genetic or chromosomal abnormality. Our chromosomes are our genetic makeup (our genes, or sometimes called DNA). The risk of fetal aneuploidy, which means conceiving a fetus with too many or too few chromosomes, is increased. We are supposed to have 46 chromosomes. Most of the time patients are aware of an increased risk of Down syndrome (where there are 47 and not 46 chromosomes). This is a condition where the infants that are born are usually intellectually handicapped with special needs.
Testing for fetal aneuploidy can be done either by invasive or noninvasive tests. Invasive testing includes amniocentesis and CVS (chorionic villus sampling) and this is diagnostic. Invasive procedures are, however, associated with a risk of miscarriage as it requires that a needle be placed inside the woman’s uterus to get a sample of either amniotic fluid, amniocentesis, or placental tissue, which is the afterbirth ,termed CVS. The risk of miscarriage is somewhere on the order of one in every 500 procedures. Recently, new noninvasive testing of maternal blood for either hormone levels or cell-free fetal DNA (genetic material) with ultrasound examination are screening tests and require follow-up testing in patients who screen with an increased risk for some genetic abnormalities.
In addition, due to an increased risk of birth defects in older women, a detailed ultrasound in the second three months of pregnancy to assess for birth defects particularly heart abnormalities is usually performed.
There is an increased frequency of high blood pressure sometimes termed preeclampsia and gestational diabetes. Development of preeclampsia may require preterm delivery, the baby having poor growth or, in extreme circumstances, stillbirth.
Recently, studies have shown that women at increased risk for high blood pressure during pregnancy may be able to reduce their risk by taking a low-dose aspirin. This should be discussed with your provider. Testing the growth of the baby can also to be done with ultrasounds later in the pregnancy.
The most important takeaway is that, although the pregnancy has a higher risk than if you were younger, the vast majority of women having a baby over the age of 35 have a very good pregnancy outcome.
Maternal Fetal Medicine blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!