The womb lining (Endometrium) changes thickness during menstrual cycle.
During menstrual cycle the thickness of the womb lining (Endometrium) increases several folds (2-16mm). This was discovered recently. However 1400 years ago the Quran said that Allah knows every decrease and increase of the womb.
[Quran 13.8] Allah knows what every female bears, and every decrease and increase of the wombs. With Him, everything is by measure.
The thickness of the womb lining (Endometrium) depends on the stage of the cycle.
Moslems ask how an illiterate man who lived 1400 years ago could have known that there are changes in the womb?