It is important to inform your insurance company when you become pregnant. You need to be aware of what percentage of visits, tests, ultrasounds etc are covered and what you are responsible for. Some insurance companies have a deductible for the baby that must be paid. For example my insurance company has a deductible for the baby if he or she has to stay in the hospital longer than I do or if the baby is a boy and needs to be circumcised. If the baby does not need to be hospitalized longer than I do and there is no circumcision than they waive the deductible. Some insurance companies don't cover anesthesiology. Can you believe that?!
Anyways it's just helpful to know what is ahead of you financially, because when your pregnant you don't need the added stress of being surprised with expensive bills. Also read your explanation of benefits because depending on how and when your doctor submits their claims it could have a profound effect on your pocket. For example, my doctor submits one big claim not after every visit and my insurance company said that when I have my baby if the anesthesiologist submits his claim before (even one day before) my OB submits their claim that the anesthesiologist won't be covered. So it is important to know all these things.
Lastly, you have 31 days to add your baby on your insurance plan.