Re: insurance won't cover ultrasounds....
Did you get an actual denial? Usually all maternity care, visits, ultrasounds, etc., are covered at the end of the pregnancy when the provider bills a global code representing all those services. If for some reason your doctor's office tried to submit the ultrasound bill separately (it happens), then the insurance company may have denied it as being included in that global fee, which they'll pay at the end of the pregnancy. Call them up and ask them--if you haven't been getting bills for any of your other treatment, that's more than likely the case.
Though as anng45 said, some plans don't cover maternity without an additional rider...best check into that now before the baby gets here.