John Gill Commentary 2 Kings 4:17

"And the woman conceived, and bare a son at that season, when the time came round, as Elisha had said unto her." — 2 Kings 4:17 (ASV)

And the woman conceived, and bare a son at the season that
Elisha said unto her
Quickly after this she conceived, and became pregnant, and by that time the year came round, she was brought to bed of a son:

according to the time of life :
when she had gone her full time to have a son born alive, and live.