Nah, I doubt Marowaks (or Cubones, for that matter) regularly die giving birth, since you can breed them without any problems.
On the other hand, the "mom dies in childbirth" thing might explain why they won't let you breed Nidorina/Nidoqueen even though female Nidorans can breed... evolving changes something on the inside and it causes problems when they try to lay eggs. Or maybe that's even why certain legendaries (like Heatran and Latios/Latias) won't breed in captivity, even though they have obvious genders.
On the other hand, the "mom dies in childbirth" thing might explain why they won't let you breed Nidorina/Nidoqueen even though female Nidorans can breed... evolving changes something on the inside and it causes problems when they try to lay eggs. Or maybe that's even why certain legendaries (like Heatran and Latios/Latias) won't breed in captivity, even though they have obvious genders.
