Those sent forth - 77:22
For a known term.
Man remains in the womb for a known period of time:
The Sandhills/46:15
"We admonished man to do good to his parents, and his mother carries him laboriously and gives birth to him laboriously. It takes thirty months from the time he is carried in his mother´s womb to his weaning. Finally, when he reaches the age of maturity and is forty years old, he says: "My Lord, direct me to be grateful for the favor You have bestowed on me and my parents and to do good deeds with which You are pleased. Correct my progeny. I am of those who repent and submit to You."
The Pilgrimage/22:5
O mankind, if you doubt about the resurrection, (remember) We created you from dust, then from a drop, then from a suspended matter (embryo), then from an offspring whose form is definite and uncertain. Thus do We inform you. And whatever We will, We keep it in the wombs for a certain term. Then We bring you forth as a baby, and then you grow to maturity. Some of you will be terminated, and some of you will be brought to the worst age. So that he may not know anything after he has knowledge. You see the earth dry and dead, but when We rain water on it, it vibrates and swells and produces beautiful plants.
Luqman/31:14
We admonished man about his parents, and his mother carries him with great difficulty. His weaning takes place in two years. You should thank Me and your parents. To Me is the return.