Advanced Maternal Age is a term applicable to a woman who will be 35 years of age or older at time of delivery.
What is the significance of advanced maternal age?
All of the genetic reproductive material (eggs) that a woman has for conception is present at the time of birth. After the age of 35, the risk of having a genetically abnormal conception (fetus or child) increases, and is significant enough to warrant genetic counseling and contemplation of diagnostic procedures during pregnancy. These procedures evaluate fetal chromosomes (karyotype).

The most common diagnostic procedures performed during pregnancy for evaluation of fetal karyotype are chorionic villus sampling (CVS) and genetic amniocentesis.

What are chromosomes?
Chromosomes are inherited biological material present in all of the cells of the human body. Genetically normal individuals have 46 chromosomes (23 pairs) in each cell, half of which are inherited from each parent.
Chromosomal abnormalities occur when an abnormal number of chromosomes are inherited from a parent, when one or more of the 23 chromosomes inherited from a parent have a structural abnormality, when there is abnormal pairing of the sets of 23 chromosomes inherited from each parent, or when random errors in cell division occur near the time of conception. The overwhelming majority of chromosomal abnormalities is not inherited and can not be caused by environmental exposures during pregnancy. Chromosomal abnormalities can occur in anyone’s pregnancy but the risk increases with a woman’s biological age.
Other risks associated with AMA
With increasing maternal age there is an increased risk of medical complications that may have adverse effect on pregnancy. Examples include hypertension, endocrine disorders such as diabetes and thyroid disease, rheumatologic disorders such as lupus, pulmonary and cardiac disease, gynecological abnormalities such as fibroids, and rarely malignancies. Additionally there is an increased risk of adverse obstetrical outcome, especially in a first pregnancy, including glucose intolerance, hypertensive disease, and complications associated with preterm birth. Apart from fetal chromosomal abnormalities there is an increased risk of congenital malformations especially after the age of 40. These malformations are not detected by CVS or amniocentesis testing.
Testing options available for AMA
It is considered standard of care to offer all patients of advanced maternal age prenatal diagnostic evaluation of fetal karyotype by either CVS or genetic amniocentesis. These procedures are not without some degree of risk therefore genetic counseling regarding age specific risks of chromosomal abnormalities and the available diagnostic or screening options is recommended for all patients. Screening tests may reduce the risk of chromosomal abnormalities but do not exclude them. Regardless of fetal karyotype or maternal screening results additional testing for AMA should include detailed ultrasound assessment for fetal congenital abnormalities at 18-20 weeks of gestation.