Broken down, emotions out of it, pregnancy is a mere risk of sex, like an std.
So people are fine with a woman being punished with pregnancy but not std? How does that work, they both came about the same way, through sex. Both have unwanted consequences for the woman if left untreated.
I don't think the most adamant of pro-lifers is coming from a position of wanting to 'punish' the woman. If that were the case, there would be widespread calls to make putting a baby up for adoption illegal unless the parents had died or were simply physically or mentally incapable of safely raising them.
The concern is for the new human life that is being extinguished - I don't think anybody is wanting to force the mother to bring up an unwanted child for the next 18 years - or even necessarily a minute longer than necessary, after the birth, once another adult is able to step in take over all caring responsibilities for the child.
An STD is not a sentient human organism and is universally considered to be a valueless parasite. Please tell me that you really don't view humanity as a whole that way (granted, some people do grow up to make horrific choices with how they decide to live out that life - never before they're born, though)?
If I had a broken radio, stuck on top volume and out of tune, that wouldn't stop hurting my ears with a horrible tinny cacophony, I could take a hammer to it, smash it to pieces and hurl it in the bin, with no moral issues - because it's just a thing.
If I was similarly driven crazy by my neighbour's incessantly barking dog, there are a number of avenues I could reasonably explore to try to resolve or ameliorate the issue, but going around there and taking a hammer to its skull would be universally condemned as a horrifically barbaric thing to do.
Sorry if that's quite a violent analogy, but it's exactly the thought that springs to my mind when the value of a human life is compared to that of an STD.