Sing, O barren, you that did not bear; break forth into singing, and cry aloud, you that did not travail with child: for more are the children of the desolate than the children of the married wife,
says the LORD.
Read Chapter 54
George Leo Haydock
Barren Jews in captivity, or Church of the Gentiles, to which alone many of the expressions can be applied. (Calmet)
The Gentiles were before unfruitful, as the Jews will be till towards the latter times. (Worthington)