As with many prophecies, this one had an initial and a final fulfillment. The initial fulfillment was in the great sorrow of Israel when most of her people were carried away into Babylonian captivity. The final fulfillment is here in Bethlehem. Imagine the cries of the mothers and grandmothers throughout the village. Though this was a horrible tragedy, the work of Christ would bring great salvation.
All children die because of sin.
However, we can also rejoice in the fact that they are with the Lord. Joseph moved his family back toward Israel. Once he executed 3,000 Jews for a revolt in which most of them took no part. There were hundreds, perhaps thousands of prophets in Israel's history. It seems that this saying, though not a part of Scripture was common knowledge revealed to many of the prophets.