This has gotten asked in the comments, and since I actually knew the answer, AND because I freaked out during the Open Mic when I heard it, I figured it was worth a post: the song that was playing when Matt’s mom was pregnant and meeting with Angelo Filipelli was “Rush Rush” by Paula Abdul.
They chose this song because it was released around the time that Matt’s mom would have been pregnant with him, so it gives a good indication of the timeline during that scene. But let’s just take a minute to talk about the video, which I have embedded below. “Rush Rush” was the first single off of Abdul’s second album, Spellbound, so she wanted to make a really big video.
The clip is Over six minutes long and begins with a 90-second mini-movie starring Paula Abdul and Keanu Reeves(!), that is basically a giant homage to Rebel Without a Cause(!!), except that Keanu Reeves has crazy floppy hair and doesn’t look like he’s in the 1950s even a little bit. The entire thing is completely incomprehensible, but oh, how I loved it when I was a kid. Seriously. Watch the video. It’s probably the best thing you’ll see all day.

I didn’t recognise it. I had to check when it charted.
Younger Keanu Reeves, how I loved him in the original Speed. And he’s rather nice in Much Ado About Nothing, even if his performance is not!