My husband and I are self-insured and were at the time that I was pregnant with each of my children. We looked into the cost of maternity coverage prior to getting pregnant with our first child (who is now 4). Things may have changed, but at that time you had to have the coverage for 9 months before you could get pregnant and at a cost of a minimum of $300 a month for maternity coverage, we figured it was cheaper to pay for my pre-natal care, labor, and delivery out of pocket. We discovered that every provider would give us a discount for paying cash. With our second child, we discovered that the by paying cash prior to actually going to the hospital for the delivery, our bill was 1/3 to 1/2 of what it would have been because we had paid in advance. The only caveat to that is if you have anything come up during labor that will require something other than traditional delivery. If you know it's coming, I suppose you could make arrangements with the hospital to pay for that in advance as well. In the long run, we saved money by paying for everything with cash rather than the maternity insurance.
Good luck!