The answer is: 90

Gen 17:17 / 21:5

Sarah, the wife of Abraham, became a symbol of miraculous childbirth when she gave birth to Isaac at the age of 90. This incredible event serves not just as a pivotal moment in the Genesis narrative, but as a profound testament to resilience, hope, and the lengths to which divine promise can unfurl even against the odds. Sarah initially laughed when she heard the news that she would conceive, humanly embodying disbelief and wonder, a reaction many can relate to when faced with the improbable in life.

Interesting trivia: Sarah was likely the first woman mentioned in the Bible to give birth at such an advanced age. Her story symbolizes faith in waiting for the fulfillment of a promise, even when life might suggest otherwise. And here's a touch of biblical fun—Isaac's name means “laughter,” representing not only the joyous outcome of Sarah and Abraham’s extraordinary journey but echoes that God’s timing often comes with a sense of humor.

Moreover, Sarah's longevity also leads to interesting reflections on life stages. Many find it inspiring that great things, like Israelites’ destiny as a great nation stemming from Abraham and Sarah's lineage, arise from waiting and what might seem impossible. It suggests that our life’s special moments don’t always have to happen according to a worldly timetable—they may come when we least expect them, creating a story of faith to inspire future generations.