Resisting arrest is NOT an option.
If the police didn't have the right to impose non-negotiable commands, then their authority would cease to mean much.
Perhaps tasering seems extreme, but what are the other options really?
Pepper Spray: Does this stuff get absorbed into the bloodstream, posing a health risk to a fetus? I don't know the answer to that for certain, as I'm sure the cops don't either.
Baton: An errant swing could hit her belly, so that's a risk to the fetus.
Pure brute force: Jerk her out of the car, and maybe she falls face-first and smucks her belly on the pavement. Potential disaster.
The cop was in a precarious position. Remember, he can't just say "Ah, what the hell, it's just a speeding ticket" and let it go. He has to enforce the rule that says if you don't sign the ticket, you must go to jail. It's NON-NEGOTIABLE. The minute she refuses to sign, and then refuses to step out of the car, it's not a simple speeding ticket anymore...it's RESISTING ARREST. She is solely responsible for putting her baby at increased risk.