Genesis 20:17

‘VAYEILEIDU’ (AND THEY BORE CHILDREN). If this is understood literally as referring to his wife, and his maidservants and stating that the Eternal had restrained their wombs, it is astonishing! For it appears that on the first night that Sarah was taken to Abimelech’s house, and he had not even approached her, G-d immediately came to him in the dream, and in the morning he rose early and called his servants and also Abraham. When then did they experience this restraining of the womb? Perhaps it so happened that they were in their due time, experiencing the pangs of childbirth, unable to be relieved by giving birth. Perhaps, also, Abraham delayed his prayer for many days. But according to this interpretation, the nature of Abimelech’s healing as well as his sickness have not been explained in Scripture.
Now Rashi comments: “Vayeileidu — and they were relieved, their channels were opened, and they brought forth their wastes. This was the leidah (bringing forth) as it referred to them. All the wombs means every opening of the body.”
But this is not correct. Even if we were to say concerning the word vayeileidu that it means “bringing forth” — as we do indeed find the word leidah used in many contexts, such as: Yea, he conceiveth mischief ‘veyolad’ (and bringeth forth) falsehood; Before the decree ‘ledeth’ (bring forth); for thou knowest not what a day ‘yolad’ (may bring forth), meaning what the days will bring forth and originate — but the word rechem (womb) never refers to any other openings. This is not contradicted by the verse, Or, who shut up the sea with doors, when it broke forth, and issued out of the womb, for this is merely a figure of speech,,) similar to “the belly of the earth.”.
Now Onkelos’ opinion is not like that of the Rabbi for even if he translated, “and they were relieved,” yet the word rechem (womb) he renders literally as “the opening for giving birth to a child.” However, [the reason why Onkelos translated it, “and they were relieved,” and not “and they gave birth,” is that] he wanted to include Abimelech also in the word vayeileidu.
In Bereshith Rabbah it is said: “For the Eternal had fast closed up (‘atzor atzar’), i.e., closed up the mouth, closed up the neck, closed up the eye, closed up the ear, closed up above, and closed up below.” Now the Rabbis derived this exposition from the double usage of the expression, …

ויתפלל...את אבימלך, he again possessed an active libido, just as he had before G’d struck him.

ואת אשתו ואמהותיו, the ones who had been supposed to give birth but had been unable to due to this affliction. Even though, generally speaking, we cannot determine precisely when a baby that is due to be born will be born, the women who had entered labour at the time the affliction struck could not give birth so that it was clear what the affliction was connected to. After Avimelech had dreamt the dream which the Torah described in detail, he called together both his servants as well as Avraham early in the morning. If so, when did they experience the impediment to delivering the babies due? Perhaps they experienced labour pains which were not relieved for even brief periods in between. Or, perhaps, Avraham took his time before he appealed to G’d in prayer to relieve the situation. We know that when women are in labour there are a number of ways in which their husbands can alleviate their pains and bring on the birth. All of these attempts had failed so that it became clear that some supernatural power had its hand in what was happening.

וילדו, this word may refer to Avimelech’s wife and his maidservants; alternately, it may refer to Avimelech’s ability to ejaculate semen again, something he had not been able to do. Onkelos translates this as ואתרוחו, meaning that their orifices which had been closed opened up again. Why would he not translate the word וילדו as “they gave birth?” Perhaps what he meant was that they did give birth, and he did not really mean that their orifices had been closed so that they could neither urinate nor defecate, as seems to be the opinion of our sages (Baba Kama 92b).