Kylie Jenner Shows Off Kim K's New Baby, Chicago West, in Pregnancy Video

Kylie Jenner didn't just make a big news this weekend regarding her own birth ... she also fully showed off Kim Kardashian's new baby in the process.

Kylie put newborn Chicago West on full display Sunday in a pregnancy montage video she posted as part of her announcing her birth this week. You see Kim handing over baby Chicago to a then-pregnant Kylie ... and the camera zooms up on her face.

It's among the first clear shots of Kim's third child -- there was another good shot taken earlier this week of Chicago in a stroller.

As we reported ... Kylie broke the news Sunday in announcing her Thursday birth. She says her baby girl is "beautiful and healthy" ... no word on a name yet, though.