Women's Health Specialists of St. Louis
Obstetrics and Gynecology

Articles - Advanced Maternal Age

Advanced maternal age is a term used for women who will be 35 before the time of delivery of their baby. Nothing magical happens at age 35. It is a time when the risk of having a baby with Downs syndrome or any other chromosomal abnormality increases to a statistically significant number. For example, at age 35, the risk of having a baby with Downs syndrome increase to about 1/380 and the chance of having a baby with any chromosomal abnormality increases to about 1/200. Though this risk is much greater than a woman in her twenties, the risk is still less than 1% of having a child with a chromosomal abnormality. After age 35, the risk of chromosomal abnormalities increases rapidly so that by age 45 the risk is approximately 1/20 or 5%. The risk of chromosomal abnormalities increases with age because the eggs or oocytes that women have are actually present before we are born. With increasing age, the eggs are less likely to grow or divide properly. When the eggs divide unequally then the chromosomes are unevenly divided in the cells. Downs syndrome for example, is when there are three rather than two copies of chromosome 21 present in the cells. Chromosomal abnormalities like Downs can make conception more difficult and can cause recurrent miscarriage. Thankfully, new non-invasive techniques to help detect chromosomal abnormalities early in pregnancy are being developed. Most recently, first trimester screening has been made available. This screen involves an ultrasound of the baby and the measurement of two hormones of pregnancy from moms blood. During the ultrasound, a picture of the babys profile is obtained and the skin on the neck is measured. The combination of the blood test and ultrasound makes this test 85%-90% sensitive for Downs syndrome with a 5% false positive rate. This test is now considered to be a better test than the blood screening tests offered in the second trimester. The gold standard test for detection of chromosomal abnormalities is still amniocentesis. Amniocentesis is when amniotic fluid is removed from around the baby. This fluid contains cells from the baby which can then be grown and chromosomes can be directly analyzed. The sensitivity of this test is as close to 100% as currently possible. The problem with this test is that there is some risk involved in the removal of the fluid from the sack around the baby. The test is not performed until the second trimester.

Though chromosomal abnormalities are the biggest concern for women 35 and older who desire pregnancy, there are other risks that increase as well. Coexisting medical conditions become more common as we age and may cause complications with pregnancy. High blood pressure and diabetes are the most common medical conditions that occur. With increasing age, moms also face an increased risk of having babies born prematurely.

Though these risks require consideration, they should not necessarily prevent a woman from choosing to attempt pregnancy. In fact, the fastest growing population of pregnant women, are those over the age of 35. The American College of Obstetricians and Gynecologists have recognized the need to provide literature and support for this group of mothers and has recently begun production of a magazine specifically for women 35 and older entitled PLUM. Women who are 35 years of age or older and considering pregnancy should discuss these issues with an OB/GYN in order to understand their personal risks.