See the later update. Basically, this is a law where to divergent and opposing viewpoints can come together on a single issue but for different reasons.
First, you have the anti-abortion crowd which wants to fight to get some form of recognition that a fetus or unborn child is a legally a person. Once you get this acknowledgment, you can do some incremental legislation granting this "person" more and more rights until abortion is illegal.
Second, you have womens' organizations and womens' rights group which, considering the fact that murder is the leading cause of death among pregnant women aside from medical complications, want law to protect pregnant women. The additional charge of murdering could have some deterrent effect on the murder of pregnant women. However, they want to make sure that the law does not infringe on abortion rights whatsoever, so there are disputes as to the specific wording of the bill, but some leftys will be on board with this type of thing.
So, this type of bill passes (albiet with a small majority). Of course some people view the fetus as a person, but it is a far cry from outlawing the fertilized egg and it is a far cry from what the Colorado loony tunes are proposing.