John Chrysostom

"All these are the beginning of sorrows," that is, of those that befall them. Seest thou in what a state things were then, and how manifold was the war? And this is the beginning, when each of the things to be effected most required quiet. In what state then were they? for nothing hinders us from resuming the same things again. …

Homily on the Gospel of Matthew 75 ↗

Jerome

These all are the beginnings of sorrows, is better understood of pains of labour, as it were the conception of the coming of Antichrist, and not of the birth.

Catena Aurea by Aquinas ↗

Thomas Aquinas

Someone might say: all these things happened by chance and were not indicative of sorrow. On the contrary. Hence he says, now all these are the beginnings of sorrows. Isaiah 13:8: They shall be in pain as women that are in labor. So Chrysostom explains it. But insofar as it is referred to the consummation of the world, Origen explains it thus. We should consider the world as one man, because when it tends toward death, the vital powers begin to weaken. …

Commentary on Matthew ↗