"He stopped drinking cold turkey -- and promised he won't drink again until after Kourtney gives birth," a source told Us Weekly. "Scott knew he had hit rock bottom."
Disick had an incident in June that resulted in him being hospitalized for alcohol poisoning.
Kardashian reportedly threw Disick out of their summer home in the Hamptons because of his drinking.
"[Kourtney] told him that was the last straw," the source said.
Kardashian is due to give birth in December, which means it might be a long, dry summer and fall for Disick.