Jennifer Lopez will announce her pregnancy Saturday!

The NY Post is reporting that "...Jennifer Lopez will announce her pregnancy on Saturday at her Madison Square Garden concert," said an insider.

A spy at her concert in Connecticut Wednesday night told us, "a fan blew the side of her top all the way up for a moment, and a definitive baby bump was there. She was very quick to push down her top. Then she talked about how this year is full of firsts for her . . . and every so often her dress would fly up and you would see her belly."