 The phenomenon was recognized in the late 20th century, as changes in lifespan and a later age for childbearing meant that mothers often had small children and frail parents at the same time.For example, in the early 20th century, a woman might have her first child around age 20, when her own parents were around age 40 and not typically in need of any special care.More recently, in developed countries, women often have children closer to the age of 30, when their own parents are around age 60 and therefore at much higher risk of needing support before the grandchildren have become adults.