The Smiths, This Night Has Opened My Eyes, available on Louder than Bombs. Not about abortion exactly, although people who think too much about such things invariably see a Rohrschach thereof in the first lines:

"In a river the color of lead
Immerse the baby's head"

The lyrics are pretty easy to find, but you ought to hear it sung, especially "The dream has gone but the baby is real (oh, you did a good thing) / She could have been a poet or she could have been a fool (oh, you did a bad thing)"---the delivery really will quite floor you.