Babies! Aliens! Real monsters?!

Yo. I am a bit confused about pregnancy. Not in the way you might think though. Like, I think I have the basics down about how it all happens and what not, but here is the part that I think is odd.

Why are pregnant people always, no matter how pregnant, rubbing their stomachs. I don't see how it could be calming. In fact, maybe it would only freak you out more, because I am sure, that even after 9 months, it still feels pretty foreign to have something growing inside of you. Almost, Alien. Which brings me to my next point.

You never saw that robot dude from Alien, or Aliens, or aliens, rubbing his robot, stomach. That is if robots even have stomachs, so let's say robot torso. He had sensors and stuff and he wasn't rubbing his. It's just odd. That is all I am saying. Then again, maybe he wasn't rubbing it with his hand, but he was feeling with his robot parts.