Not just women, men too have a biological clock that starts ticking at..

Women's fertility has remained closely tied to their age for multiple decades. The biological clock concept has persisted as a widespread belief, which states that women experience rapid egg quantity and quality deterioration after reaching their late 30s or early 40s. The cause for women's declining fertility during their late 30s and 40s became clear, because their egg quality and quantity decrease, and their risk of miscarriage and Down syndrome increases