Topic on discussion of heavenly truth in ancient times in the plain questions (First article part VI) [1]

The Emperor asked: “Why can some old people have children?”

Qi Bo answered: “Because they have extraordinarily long ages. The qi and blood of channels are still free, and the kidney qi is in surplus. Although being able to have a child, a man will not be older than sixty-four, and a woman will not be older than forty-nine, their essential qi is completely exhausted at this time.”

The Emperor asked: “Can people still have children, who are knowledgeable of taking care of their health and are older than a hundred?”

Qi Bo answered: “People skilled in health care can prevent senility and preserve their bodies. Though very old, they can still be fertile.”