Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(Allah knoweth that which every female beareth) whether it is a male or a female (and that which the wombs absorb) and the female whose pregnancy is less than nine months (and that which they grow) and the female whose pregnancy is more than nine months. (And everything) the increase, decrease, the delivery of the child and its stay in its mother's womb (with Him is measured).
God knows what every female bears, of male or female, one or more, and otherwise, and what the wombs reduce, of the time of gestation, and what they increase, of it. And everything with Him is according to a [precise] measure, a [precise] amount and limit which it does not exceed;
Those are hidden mysteries known only to God, who, knows what every female bears, and thus He knows what the female of the soul bears in the way of the child of perfection, in other words, the potential of every preparedness, and [knows also] the increase in the wombs of preparedness as a result of self-cleansing, self-purification and the blessed company of perfections, and [He knows] the reduction [in these preparednesses] as a result of engrossment in passionate desires. And everything, in the way of perfections, with Him is according to a, designated, measure, in accordance with [a person's] receptivity. Or [it means]: and everything in the way of the potential for receptivity is with Him according to a measure [designated] in pre-eternity issuing from His holiest effusion, neither increasing or decreasing. Or: for every folk there is a guide, who is God, exalted be He, as He has said You [Muḥammad] cannot guide whom you like, but [it is] God [who] guides whomever He will [Q. 28:56], by virtue of the fact that He knows the potential for receptivity that is in [all] preparednesses, the [potential for] increase and decrease [in them] and so He determines on that basis their perfections.
(And indeed We created man out of an extract of clay. Thereafter We made him as a Nutfah in a safe lodging. Then We made the Nutfah into a clot, then We made the clot into a little lump of flesh, then We made out of that little lump of flesh bones, then We clothed the bones with flesh, and then We brought it forth as another creation. So Blessed is Allah, the Best of creators.)23:12-14 In the two Sahihs it is recorded that `Abdullah bin Mas`ud said that the Messenger of Allah said,
(The matter of the creation of one of you is put together in the womb of the mother in forty days, and then he becomes a clot of thick blood for a similar period, and then a piece of flesh for a similar period. Then Allah sends an angel who is ordered to write four things. He is ordered to write down his provisions, his life span, his deeds, and whether he will be blessed or wretched.'') In another Hadith, the Prophet said,
(The Keys of the Ghayb (unseen knowledge) are five, nobody knows them but Allah. Nobody knows what will happen tomorrow except Allah; nobody knows what is in the womb except Allah; nobody knows when it will rain except Allah; no soul knows at what place he will die except Allah; and nobody knows when the (Final) Hour will begin except Allah.) Al-`Awfi reported from Ibn `Abbas that he said,
وَمَا تَغِيضُ الاٌّرْحَامُ
(and by how much the wombs fall short), this refers to miscarriages,
(or exceed), this refers to carrying her fetus in her womb for the full term. Some women carry their fetus for ten months, while others for nine months. Some terms are longer or shorter than others. This is the falling short or exceeding that Allah the Exalted mentioned, and all this occurs by His knowledge.'' Qatadah commented on Allah's statement,
وَكُلُّ شَىْءٍ عِندَهُ بِمِقْدَارٍ
(Everything with Him is in proportion.) "For a term appointed. Allah has the records of the provisions and terms of His creation and made an appointed term for everything.'' An authentic Hadith mentioned that one of the Prophet's daughters sent (a messenger) to him requesting him to come as her child was dying, but the Prophet returned the messenger and told him to say to her,
(Verily, whatever Allah takes is for Him and whatever He gives is for Him, and everything with Him has a limited fixed term (in this world), and so she should be patient and hope for Allah's reward.) Allah said next,
عَـلِمُ الْغَيْبِ وَالشَّهَـدَةِ
(All-Knower of the Ghayb (the unseen) and the Shahadah (the witnessable),) Who knows everything that the servants see and all what they cannot see, and none of it ever escapes His knowledge,
(the Most Great), greater than everything,
(the Most High.) above everything,
قَدْ أَحَاطَ بِكُلِّ شَىْءٍ عِلْمَا
((Allah) surrounds all things in (His) knowledge.)65:12, and has full power over all things, the necks are under His control and the servants are subservient to Him, willingly or unwillingly.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
When amplified the verse will mean : Allah remains fully aware of all the developments that take place in the child while in its mother's womb, and He watches over the decrease or increase in each of its limbs, and its potentialities, capabilities and powers.
That is, "Allah not only directly watches over whatever each person does, and is fully aware of everything he does, but He has also appointed such Guardians as accompany him everywhere and keep a full record of all his deeds." This has been stated here to warn those people who live their lives under the delusion that they have been left absolutely free to do whatever they like and shall not be required to render an account of what they did in this worldly life. The warning is that such people invite their own retribution.
This is to warn them further that they should not remain under any delusion that some holy person or saint or angel has the power to rescue them froth Divine Retribution, for there is none who could defend them against Allah, even though they might have been paying homages and making offerings to their so-called patrons and protectors in the hope that they would rescue them froth punishment from Allah on the Day of Judgment.