Would it be wrong to sign up for health insurance that covers abortion?

No, it would not be wrong for you to sign up. Your intent is to pay for medical coverage for yourself and your family, not to pay for abortion or sterilization. Of course, if you can find comparable coverage and rates through a company that does not cover abortion or sterilization, it would be best to buy your coverage from that company. Unfortunately, finding such a company in this day and age is extremely difficult.