Objection 1. It would seem that the woman was not formed immediately by God. For no individual is produced immediately by God from another individual alike in species. But the woman was made from a man who is of the same species. Therefore she was not made immediately by God.
Objection 2. Further, Augustine (De Trin. iii, 4) says that corporeal things are governed by God through the angels. But the woman's body was formed from corporeal matter. Therefore it was made through the ministry of the angels, and not immediately by God.
Objection 3. Further, those things which pre-exist in creatures as to their causal virtues are produced by the power of some creature, and not immediately by God. But the woman's body was produced in its causal virtues among the first created works, as Augustine says (Gen. ad lit. ix, 15). Therefore it was not produced immediately by God.
On the contrary, Augustine says, in the same work: "God alone, to Whom all nature owes its existence, could form or build up the woman from the man's rib."
I answer that, As was said above (2, ad 2), the natural generation of every species is from some determinate matter. Now the matter whence man is naturally begotten is the human semen of man or woman. Wherefore from any other matter an individual of the human species cannot naturally be generated. Now God alone, the Author of nature, can produce an effect into existence outside the ordinary course of nature. Therefore God alone could produce either a man from the slime of the earth, or a woman from the rib of man.
Reply to Objection 1. This argument is verified when an individual is begotten, by natural generation, from that which is like it in the same species.
Reply to Objection 2. As Augustine says (Gen. ad lit. ix, 15), we do not know whether the angels were employed by God in the formation of the woman; but it is certain that, as the body of man was not formed by the angels from the slime of the earth, so neither was the body of the woman formed by them from the man's rib.
Reply to Objection 3. As Augustine says (Gen. ad lit. ix, 18): "The first creation of things did not demand that woman should be made thus; it made it possible for her to be thus made." Therefore the body of the woman did indeed pre-exist in these causal virtues, in the things first created; not as regards active potentiality, but as regards a potentiality passive in relation to the active potentiality of the Creator.
Source: Summa Theologica (New Advent)