לָכֵ֣ן יִתְּנֵ֔ם עַד־עֵ֥ת יוֹלֵדָ֖ה יָלָ֑דָה וְיֶ֣תֶר אֶחָ֔יו יְשׁוּב֖וּן עַל־בְּנֵ֥י יִשְׂרָאֵֽל׃
Therefore will He give them up, Until the time that she who travaileth hath brought forth; Then the residue of his brethren shall return with the children of Israel.
Rashbam
כעת חיה, she would give birth at the appropriate time. The word appears in this context in Michah 5,2 כעת יולדה בן,”until she who is to bear has given birth.” It is also found describing the state of Jewish mothers giving birth as being equivalent to that of midwives. (Exodus 1,19)