Doctors office issue

The facility is saying I need to pay them 4500 for prenatal care starting at my 8 week ultrasound so I will be paying 600 every visit but we have Blue cross blue shield but they are saying we have to pay out coninsurance and half of our deductible? And that the insurance will only cover vaccines? And Only 60% of ultrasounds and tests I thought all prenatal visits were covered without co pay under the law?