The comparison you offer is a false equivalency. No one forces a pregnant woman to give birth at gunpoint. A pregnant woman giving birth is a natural process; it is nature taking its course. An abortion is an artificial intervention.

The vas deferens remaining intact is, like giving birth, nature taking its course. A vasectomy, like an abortion, is an artificial intervention.

Equating abortion to prohibiting men from getting a vasectomy would be a more valid comparison.