The Heights - 7:189
"He created you from a single soul (with the same genetic characteristics). And from him He created his mate so that he might find rest. When he approached his mate, he loaded her with a light burden and traveled with her. When his burden became heavy, they both begged their Lord, Allah: "If you give us a perfect child, we shall be among the thankful."
Related:
The Thunder/13:8
Allah knows what every female bears and what the wombs decrease and increase. With Him everything is according to a measure.