It appears that Isaiah is jumping back to prophecies of Zion. See below.

• Verse 15 – The nation increases when Israel is gathered, after being scattered (removed) to the ends of the earth.
• Verse 16 – Being chastened by the Lord helped bring about understanding.
• Verse 17-18 – Likening the birth of Zion to the birth of a child – painful but worth it in the end. This same comparison is included in Songs of Zion No. 62, “Hear the Call Across the Water” (see below).

Songs of Zion #62 – “Hear the Call Across the Water”
Hear the call across the water, there’s excitement in the air.
For the Mother’s been delivered, and she wants her fam’ly there.
It’s a nation born in sorrow, but the sorrow’s soon forgot,
When the mother sees the baby that the labor pains have brought.
Call the poorest cast off people from the corners of the earth,
For the mother wants her children home to celebrate the birth.

The time will come (after Christ comes) that people will resurrect from the dead.

This appears to reference the time of the destruction prior to Zion. It sounds like it’s telling people to try to hide from the destruction but, more likely, it means be right with Christ and then you won’t need to fear the destruction. It’s similar to the time of the original Passover when the blood of the lamb on the door was enough for the death angel to pass over.

“For the time soon cometh that the fulness of the wrath of God shall be poured out upon all the children of men; for he will not suffer that the wicked shall destroy the righteous. Wherefore, he will preserve the righteous by his power, even if it so be that the fulness of his wrath must come, and the righteous be preserved, even unto the destruction of their enemies by fire.  Wherefore, the righteous need not fear; for thus saith the prophet, they shall be saved, even if it so be as by fire.” (1 Nephi 22:16-17)