Any woman who is 35 or older and goes to the doctor after becoming pregnant will most likely hear the term “advanced maternal age”. While that may not be the best term to use and would make anyone feel older than they really are, what exactly does it mean and why are women classified that way once they hit 35?
Women are born with all of their eggs. In comparison to men, who generate millions of sperm every day, women ovulate, or release an egg, once a month from the time they hit puberty. Since women are born with all of their eggs, as women get older, so do their eggs. The genetic instructions inside each of their eggs are slightly more prone each year to making a mistake. These mistakes can result in pregnancies being diagnosed with chromosome abnormalities, such as Down syndrome, when a whole chromosome that contains genetic instructions is missing or duplicated and that mistake is repeated inside the cells of a fetus that is growing.
Understanding Advanced Maternal Age
Over the last 50 years, women are waiting longer to have children. The mean age of first births for women increased by nearly five years from 1970 to 2014, from 21.4 years of age to 26.3 years of age. This change is partly seen due to people waiting longer to get married, the availability of contraceptive options, and better opportunities for progression in a career or education. In recent surveys, women have cited a desire to achieve career, educational, financial, or personal goals before planning a pregnancy. While these changes are beneficial to women and society as a whole, it is also a well-known fact that fertility declines with advancing age, and risks in pregnancy increase for both mother and baby as a woman gets older.
While all women have risks of pregnancy complications, older women have higher risks during pregnancy. The risk of spontaneous abortion, or miscarriage increases in older women, primarily due to chromosome abnormalities and poor egg quality. In addition, risk of ectopic pregnancies greatly increases in women 35 and older. And as discussed with miscarriage, the risk to have a pregnancy affected by a chromosome abnormality, like Down syndrome, and make it to full term increases. For example, the risk for a 25-year-old woman to have a live born baby with a chromosome abnormality is 1/476, or .2%. The risk of a 35-year-old woman to have a live born baby with a chromosome abnormality is 1/179, or .6%. And the risk of a 45-year-old woman to have a live born baby with a chromosome abnormality is 1/24, or 4.2%.
With the trend of waiting to get pregnant until older, and the increased risk and complications of pregnancy when you are older, what exactly can be done to help women in their pregnancies? Advances in medicine and specifically the field of infertility have made it possible for many to conceive and carry a pregnancy when they otherwise would not be able to. Women who are older and are attempting to conceive should consult with their doctor sooner, and fertility tests are available to determine if there is a problem. In addition, methods of conceiving such as intrauterine insemination or in vitro fertilization are continually improving and providing successful pregnancies. Once a woman conceives, there are physicians trained in high risk pregnancies (maternal fetal medicine physicians) who can closely monitor a woman and her pregnancy for complications.
Genetic Screening & Maternal Age
Screening methods to evaluate a pregnancy for chromosome abnormalities have also improved. The majority of women over the age of 35 are offered a screening called non-invasive prenatal testing (NIPT), which screens the pregnancy for common chromosome abnormalities. It involves a simple blood draw from the patient, and fetal DNA that comes from the placenta and circulates in the maternal blood is analyzed through the patient’s blood. By looking at the fetal DNA, NIPT produces a high risk or low risk result for the common chromosome abnormalities: Down syndrome, Trisomy 13, and Trisomy 18. Most genetic testing companies will also analyze the sex chromosomes and determine the gender of the baby as well. This screening method is currently the most accurate screening method available to pregnant women.
There are also diagnostic testing options during pregnancy to test for chromosome abnormalities, such as chorionic villus sampling (CVS) and amniocentesis. Both of these testing options are invasive procedures and involve taking a sample of placenta or amniotic fluid and looking directly at the baby’s chromosomes. While diagnostic testing is the most accurate method of determining of a chromosome abnormality is present in a pregnancy, these tests also involve a risk of miscarriage due to the nature of being invasive.
If you are interested in learning more about your risks in pregnancy or advanced maternal age, are currently pregnant and interested in being screened or tested for chromosome abnormalities, or simply want to learn more, please contact AT-GC to meet with a genetic counselor.