But woe to them that are with child,.... Who because of their burdens, would be very unfit for, and very incapable of fleeing with any haste; and therefore very liable to fall into the hands of the enemy, and become their prey:
and to them that give suck in those days; who could not bear to leave their children behind, and yet would not be able to carry them with them; at least not without great trouble, and which would much retard their flight, and endanger their being taken by the enemy; See Gill on Matthew 24:19.

But woe to them--or, "alas for them."
that are with child, and to them that give suck in those days--in consequence of the aggravated suffering which those conditions would involve.