Hi there I have gone through your situation in Jan. You can get Pernatal care for the maternity care known as Chip that cover all the your expenses during pregancy included 4 ultrasound and labor.
Other is WIC that is a nutrition food coupon for mother and baby. for this you have to do Two thing
1 look for the Oklahoma health and community service and get the form and fill it out and submit in person. If you have SS then you may get Medicare for you.If not then apply for the CHIP
Best recommendation will be go to any hospital for check up and tell them you don't have insurance and you want to apply for Maternity medicare then they will help you out these are done in registration department. Before you get there find out if there are any rep for this. To be qualified you need show what is your income ? It you are working llegal then they will ask your annual income or if you are student then they will ask you the verification of your supporting person.Once these are done then you will be reciving Medicare in a 2-4 weeks.If they denies you then they or you may have to apply for the Chip. So there for find a OB/GYN in internet then talk to doctorthat accept govt Medicare and then it will works hey don't panic about it . I went through it but later it went smoothly.
Here are the docs u needed
your ID, Proof of your pregancy ,and your annual income, it doest not matter even if you are international student.
Check this site which may help you a lot. DO not hesitate man to apply . It is not only you doing this .
Need more help let me know. All the best