What does the Pasuk mean when it writes "and they gave birth, and in the following Pasuk, when it writes that "Hashem had closed all the wombs"?
Seforno: It mans literally that Hashem had shut their wombs to kill their offspring. 3
Ramban: The moment Avimelech took Sarah, Hashem closed his sexual-organs, and he was unable to be intimate with Sarah. 4 Moreover, his wife and any of his maidservants who were pregnant were unable to give birth, for the prolonged period that Sarah was with Avimelech. 5 And all this was reversed following Avraham's Tefilah.
According to the Ramban, Onkelos and Yonasan learn like the Seforno (Refer to 20:17:1:2.), and the Midrash that learns like Rashi learns 'all the orifices' from the double expression "Atzor Atzar". See Ramban's objection to this explanation.
As recorded above in Pasuk 9.
In keeping with His threat above in Pasuk 18. (See Ramban, who grapples with this explanation.)
Which is what the Torah meant when it wrote earlier (in Pasuk 6) "and I did not allow you to 'touch' her".
As is implied by "ki Atzor ... be'ad Kol Rechem".