Here, it was said: اللَّـهُ يَعْلَمُ مَا تَحْمِلُ كُلُّ أُنثَىٰ وَمَا تَغِيضُ الْأَرْحَامُ وَمَا تَزْدَادُ ۖ وَكُلُّ شَيْءٍ عِندَهُ بِمِقْدَارٍ ٍ. It means that Allah Ta ala knows everything about what every woman carries in her womb - a boy or girl, beautiful or otherwise, good or evil - and about why wombs of women decrease or increase, that is, about the time of delivery, whether early, in due time, or late.
Stated in this verse is a particular attribute of Allah Ta’ ala: That He is the Knower of the Unseen (` Alim al-Ghayb). He is aware of the minutest of this entire universe and that of everything created in it, and He is most comprehensively informed of all changing conditions of each such particle. Mentioned along with it is the fact of all-inclusive and most perfect knowledge of every stage, every change, and every trait in the complex process of human procreation. For instance, it is He alone who has the ultimate knowledge - the most sound, the most certain - of female pregnancy - a boy or girl? Or, both? Or, nothing but the accumulation of clusters of water or gas? Whatever opinion a physician gives in this matter as based on clinical indicators and educated guess cannot be taken to be any more than strong likelihood or estimate. There are times when things turn out to be otherwise. Even X-rays and more modern Imaging techniques fail to unravel the reality of this phenomena as due. We can only say that its real and certain knowledge can be credited only to Allah Ta` ala. This is what has been stated in another verse of the Qur’ an which says: (And He knows whatever there is in wombs - Luqman, 31:34).
The word: تَغِیض (taghudu: decrease) is used in the sense of becoming less or dried up. In the present verse, set against the word: تَزدَاد (tazdad increase), it becomes clear that, at this place, it means decrease. Thus, it means that the most correct and sound knowledge of 'what the wombs decrease or increase' rests with none but Allah Ta` ala. This 'increase' and 'decrease' could be referring to the increase or decrease in the number of children to be born, that is, whether the womb contains only one child, or has more than one. It is also possible that it may be denoting the increase or decrease in the period of actual delivery of the child, that is, in how many months, days, and hours, this pregnancy will translate into the outward physical existence of a human being. This too is something the absolutely certain knowledge of which cannot be claimed by any-one other than Allah Ta` ala.
Tafsir authority Mujahid has said that the blood excreted by a woman in pregnancy becomes the cause of decrease in the size and health of the fetus. The Qur’ anic expression: تَغِيضُ الْأَرْحَامُ ('the wombs decrease' ) means this decrease - and the truth of the matter is that the words of the verse cover decreases of all kinds, therefore, no contradiction exists here.
Said in the last sentence of verse وَكُلُّ شَيْءٍ عِندَهُ بِمِقْدَارٍ (And everything has measure with Him). It means that there can be no decrease or in-crease from the norm set with Allah Ta’ ala. All states through which a child-to-be-born passes are also included under this statement, that is, everything pertaining to such a child lies determined with Allah who knows for how many days the child will stay in the womb, then, for how long it will continue to live in the world, and how much of sustenance it will receive. This matchless knowledge of Allah Ta` ala is an open proof of His Oneness (Tauhd).