Zombie Apocalypse Pregnancy thoughts

I'm planning a zombie story, (with numerous female characters) and came upon an interesting question.

In select Zombie Apocalypse stories, a woman is pregnant. This is usually handled in various ways, marking the woman for death, or others through the will of the writer making her kill proof. In contrast to the "Last Man on Earth trope" (where most guys would say lots of fun) I can't help but wonder what is the natural female role in such a situation.
 
What would logically (not concerning censorship of readers) be the role of a woman in the desperate times of an 
Zombie Apocalypse:
 
To birth the new world, while her partner fights the advancing undead?
 
Or to free up her energy to fight the undead with him?
 
Or a third option, your thoughts.

" @LyonGod: BTW, I'm not recommending you put rape in your story. A better option would be to have the woman become pregnant (by a male friend who's stuck by her throughout the entire ordeal) at the END of the story. That way she can help fight the zombie threat, and then at the end, give the reader hope that the human race won't die off. "

interesting.