To those who have always had employee sponsored health insurance, one of the biggest surprises is that maternity is not always covered. There are a dozen states that mandate it needs to be covered under every health plan, and in the remaining 38 there are some providers that do cover it. If you are not going to be having children, being in a state that does not require it means you will likely see lower premiums. The cost of maternity is high and if it is covered that cost is spread out over all members.
The best way to cover the expenses of maternity is to have a well planned out pregnancy. Don't wait until you are pregnant to start looking for maternity coverage. Pregnancy is considered a pre-existing condition. A very high percentage of pregnancies are unplanned so even if you're not actively trying, make sure you are covered.
If you don't have a plan that covers maternity care, one of your best options is to use an HSA to pay for it, and to shop around to various hospitals. Even using a midwife can greatly reduce the cost of a normal, healthy pregnancy.