maternal age effect

Full Definition

The maternal age effect describes the well-established correlation between increasing maternal age and the risk of chromosomal abnormalities, particularly trisomies, in offspring. This effect is most pronounced for trisomy 21 (Down syndrome), where risk increases exponentially after age 35. The mechanism is thought to involve deterioration of cohesin proteins that hold sister chromatids together during meiosis, leading to increased nondisjunction events. This relationship forms the basis for age-based prenatal screening recommendations.

Usage

Usage note: Hyphenate when used as a compound adjective (maternal-age-related risk).

In Context

• "The maternal age effect explains the increased trisomy risk in pregnancies after age 35." — Prenatal counseling documentation
• "Screening recommendations are based on the well-documented maternal age effect." — Clinical practice guideline