Pregnant female soldiers.

Female soldiers in the US military get pregnant to avoid tours to combat zones. Some are also getting pregnant in a combat zone. 

Why did they sign up in the first place? If you sign up voluntarily to military service, you know you agree to all the risks and control over you. 

Who let them get pregnant? 

She did. Now, it can be suggested that female soldiers must be temporarily sterilized. 

Should they be punished?

Why not? Militaries punish their members all the time for many reasons. But then if you punish a pregnant soldier for getting pregnant, the child deserves an explanation. 

And women should be responsible enough, having gained all these rights and privileged status in society and military. 

Besides, breaking the rules in the military means breaking the contract and allowing possibility of punishment. So from a military standpoint, it's fine. 

Or, the alternative is to give them maternity leave or a desk job, even though that will put a strain on resources. 

It is in the inherent nature of all human beings to reproduce, even when you're getting shot at. 

For most other armies in the world, the simple answer is to limit specialties open to women, because these issues complicate management and resources. It does make sense, because what's going to happen if the infantry start getting pregnant, and a casualty has the potential to become two casualties. 

A more insane view is that when anyone in the military is a tool, not a person, and malfunctioning tools get replaced. So pregnant soldiers get out. If you think that is a ridiculous way to put it, then it still doesn't change the fact that an ideal army would compose of machines, not human beings. The issue of pregnant soldiers is just one of many issues that happen because we are human beings and soldiers are not ideal fighting machines many people like to think they are.  

My ideal military "war machine" would consist of all citizens who volunteer to be trained in a specialty. No separate book of rules, minimal pay, mostly part-time, just a set of standardized weapons, combat uniform, high common training standards and information network. Transportation are mostly convertible between military and civilian uses, so cost of running things are compensated. 

Rapid reaction forces are the only professional soldiers.