Advanced Maternal Age Pregnancy (AMA): This refers to any woman that is either 35 years old or will be 35 years old at the expected time of delivery of her baby. The reality is that from a medical standpoint, a 35 year old woman is young. However, from a pregnancy standpoint they are older than the average patient. This age group is commonly considered “high risk pregnancy” for several reasons.
There are several conditions that are more common in women >35 such as pre-existing hypertension, diabetes, and heart disease. Women in this age group are also more likely to develop related pregnancy conditions such as preeclampsia, gestational diabetes, and peri-partum cardiomyopathy. These conditions will be discussed separately since they are not exclusive to advanced maternal age.
Although the mentioned conditions can be challenging during a pregnancy, the biggest concern for these patients is usually the risk of abnormal chromosomes (aneuploidy). In simplest terms, with an increase in age, there is an increase in the likelihood of having a wrong number of chromosomes in the egg that will eventually become the baby. This happens because women do not make new eggs during their life like they do with other cells of the body. In fact, all the eggs that a woman will have available during her lifetime are present by the time she is born. This prolonged arrested state of the eggs along with other time related factors, increase the chances of chromosomes separating unequally with advanced age.
How we manage an advanced maternal age patient depends on what the patient desires. At a minimum, these patients should be offered specialized screening tests during pregnancy to determine if the risk is high or low. Common tests available involve drawing blood from the patient and checking for certain hormone levels according to how far along they are in their pregnancy. More recently, advanced early ultrasounds can be performed to look at “nuchal translucency“, or the thin fat pad along the back of the neck of the fetus. This is particularly sensitive for Trisomy 21 (Downs Syndrome) babies that tend to have a thickened nuchal fold.
More recently, there has been a development of tests that detect tiny amounts of DNA secreted by the baby into the mother’s bloodstream. These tests claim a high detection rate for abnormalities, but are most sensitive when used together with the tests mentioned previously.
Detailed ultrasound (Level II) is another tool available to screen for chromosome abnormalities. A reasonable percentage of babies with Downs Syndrome, Edwards Syndrome, Patau Syndrome, and Neural Tube defects will have characteristic ultrasound findings.
Regardless of which test or combination of tests is used, patients need to understand that these are all screening tests, and as such, should not be used exclusively to make a diagnosis. Although these tests are very good at telling us when a patient does NOT have an abnormality, they are not as good at telling us when their is a problem. This is because these tests have a high false positive rate. It is important that patients understand this before undergoing testing, so that a positive test does not cause unnecessary anxiety.
So what happens with a positive test? The patient should be counseled and offered more invasive tests if they want to confirm a diagnosis. These tests are Chorionic Villus Sampling (CVS) and Amniocentesis. The choice of which is appropriate depends on how far along is the pregnancy. CVS is performed very early, but does have a higher rate of complications than amniocentesis which is performed a little later in pregnancy.
These tests involve the introduction of a needle into the uterus to obtain some of the fluid around the baby. This fluid is then analyzed for the correct number of chromosomes in order to either discard or confirm the findings of the preceding screening test.