Kim's been open about her pregnancy struggles, suffering from placenta accreta -- a potentially life threatening condition -- during both. We're told docs have told her it's nearly a guarantee she'd get accreta again, putting her and her baby's lives at risk.
A source close to the family tells us Kim is also scared of another extremely painful birth, like the one with Saint ... and that's helped her make the decision easier.
However, we're told the couple is completely cool with capping off their brood at two kids. Our source says they're plenty busy with North and Saint and a new addition would be just too much.
As for Saint West -- we're told he's the perfect baby -- eating great, sleeping a ton and barely crying.
But what would you expect from the offspring of two of Hollywood's finest?