the following SHOULD NOT BE AN INSULT IN ANY WAY- i just used this comment above as a little "spark"
3 questions to think about:
1. where is the border between abort or not-abort?
2. who makes this border?
3. what are factors on which the decision (or the borders) should be made? (mental or physical disability, life expectance, costs for therapies, right to live, worth of living, burden for the family,...)

add. question 4:
when does life begin? because "murder" is the intentional kill a living thing... you could say that life begins when the baby's born or at a certain state of the embryonal genesis

with aborting you also have to take care of the all the disabled people: if you suffer from pku (phenylketonuria) like my little cousin, an illness where you can't absorb a protein and on the effect you'll get heavily mental disabled but if you make a diet ALL LIFE LONG with phenylalanin-poor nutrition nearly nothing will happen to you- mentally and physically. so if you have this illness and read or hear that a mother aborted her baby when it came out it had pku because the mother doesn't want to have a child with pku cause it's a real heavy burden (nutrition is DAMNED expensive, the first years you have to visit the doc ~ 15+ times a month, you have to get a specialist on this illness yourself so that you know how much of this protein is in which nutr., what are the signs of an overdose of phenylalanin,...........)
you're gonna be thinking a lot about your illness, about your right to live and it'll come to your mind what YOUR mother would've done IF she had known before

if you (=own decision) abort a baby for any medical reason then all the living humans with that disease will be scared of their right to live. further on if you allow the abortion of disabled babies BY LAW then you kind of take away all the living humans with that disease the right to live. the next step which isn't too far off is to oblige people to abort their babies when they have a certain disability you would have to control every pregnancy which would result in a "brave new world". don't say that i'm phantasizing- just look at what was done in the 3rd Reich...

to get back to my little exapmle:
it was just one example of one disease from an uncountable amount of diseases and i named it because it's in my family- the boy is now 7 years old, started school this year and is (besides of him being lil (but sweet) pest ) mentally and physically normal- the only thing is that his pigmentation is a bit too light which is a small sideeffect on pku but if you don't know that you'll think he's just blond