Why age 35? Do we drop off some mystical health cliff on that birthday? The age of 35 was chosen to define “geriatric pregnancy” (now called “advanced maternal age”) because, back when amniocentesis first became common, the math tipped. At 35, a woman’s chance of having a baby with a chromosomal condition like Down syndrome (which amnio tests for) was higher than the risk of losing the pregnancy from the amnio procedure itself. It was never about some age where everything suddenly changes — it was just a numbers game based on the technology available in the 1970’s when the term “geriatric pregnancy” was defined. Even though procedures are a lot safer now and we have way better screening options, the “advanced maternal age” label stuck — mostly because insurance and medical coding needed a line to draw. Did you know this about the term “geriatric pregnancy”?