Chimp mothers know all about this, giving birth without assistance:

As Erik sped north on Southwest Pacific Highway, an unusually fast labor forced Jennifer to deliver her own baby in the moving car. By the time the Scharffenbergs reached Oregon 217, Sadie had arrived in the passenger seat, unassisted, just minutes after they'd left home. Erik heard a surprising, yet reassuring sound: The new baby let out a cry next to him.
What's new, and what might very well be an American thing, is the trend of giving birth in moving cars.