File a complaint with the DC's Departmenet of Insurance, Secuirities, and Banking (DISB). DISB is the regulator for insurance policies issued in DC, including your plan. Here is a link to DISB's Consumer Alert on filing a complaint:
http://disb.dc.gov/disr/frames.asp?doc=/disr/lib/disr/pdf/Final_Health_Services_DOC_4.pdf.
Do NOT delay. Once you are denied benefits or a claim, you can file a complaint with DISB.
I'm not familiar with your specific plan, so I don't know if maternity benefits are included in your policy. They are not required by law to be a covered benefit. DISB will tell you whether they are or not.
After 2014, when federal health care reform changes kick-in, maternity and newborn care will be required coverage under ALL health plans.
Good luck.