But did he vote for it before he voted against it?

As I've posted elsewhere, Kerry wants to keep D&X, dilation and extration legal in order for that medical option to be available if the mother's life or health were at risk.
D&X (partial birth abortion) has been used to remove a brain-dead fetus. The fetus has no brain except for the basal stem which controls reflexes like kicking. Sometimes, these anomalies are not detected in the unborn baby until after the 1st trimester. This kind of abortion is available to the mother when it is determined that the baby will not be viable after birth. The fetus is kept alive only by the mother's placental nourishment.
The cranium is swollen with fluid, so the cervix is DILATED as much as possible, the fluid is EXTRACTED, to reduce the size of the head so that the baby can come out of the mother.
Kerry is not pro-abortion, but he would like this medical procedure available for these very very rare instances. Or the other choice could be for your wife to carry a non-viable fetus to term, to be delivered via c-section (the head is too big to deliver vaginally), after 9 months only for it to die slowly over hours or days (perhaps experiencing seizures, but it appears not to feel pain since it has no brain).