Albert Barnes Commentary 1 Kings 14:17

"And Jeroboam`s wife arose, and departed, and came to Tirzah: [and] as she came to the threshold of the house, the child died." — 1 Kings 14:17 (ASV)

By this time, Jeroboam had moved from Shechem and established a new capital in Tirzah, one of the old Canaanite towns (Joshua 12:24). It was a town renowned for its beauty, considered in that respect comparable to Jerusalem (Song of Solomon 6:4). Tirzah can likely be identified with “Telluzah,” a place in the mountains about nine miles from Shechem (Nablus), or with Teiasir (according to Conder). It may have been the palatial residence of the kings rather than the country's actual capital. It remained the capital until Omri built Samaria (1 Kings 16:23–24). Toward the close of the kingdom, it appears again as the city of Menahem, who murdered and then succeeded Shallum (2 Kings 15:14).

The threshold of the door—literally, “the threshold of the house.” Compare this to the prophecy in 1 Kings 14:12. The child actually died as her mother crossed the threshold of the palace. The palace, like that of Sargon at Khorsabad, was probably located at the outer edge of the town.