Look at it this way:
The man puts in a few minutes work. Strictly speaking he contributes NOTHING to the child other than a tiny bit of DNA and some cytoplasm until after it's born.

The woman spends spends 9 months undergoing massive biochemical alterations, has a range of health risk factors come into play - both emotional and physical - and has virtually every aspect of her life altered by the experience.

That said - giving the woman the power in regards to the abortion decision may require re-evaluating the concept of child support payments.