Hey there ladies! I usually only lurk here, I post regularly on PGAL. Thought I would chime in my 2 cents here. I actually work for a medical equipment company in the billing office and do all our breast pump billing. Every insurance is going to vary in their medical policy, and it can even vary from plan to plan, depending on how it is underwritten.
Most plans will not cover a breast pump for a mom and baby who are both home and there are no feeding issues present. This is considered a convenience, not a medical necessity. However, if baby and mom are separated (ie- baby in NICU), most companies will pay for the rental of a "hospital grade" breast pump while the baby is in NICU. In this case, most ins companies will require additional info, like the History and Physical/ Admission papers for baby in NICU.
If baby is home, and there are feeding issues present, pumps can still get covered, but for this kind of coverage it is diagnosis driven. Most doctors will write a script for a pump and put a diagnosis of "Newborn Feeding Issues" which most companies will deny as the pump is billed under the mom, not the baby, and the diagnosis is only valid for a newborn. However, if your OB will write the script with a diagnosis of "Postpartum Breast Engorgement" or something having to do with the mother, then in most cases, the pump will be covered. There is a list of diagnoses that will get a breast pump covered, and anything outside of that list of diagnoses will get denied.
This will all be a moot point in 2014, when more of the "ObamaCare" regulations go into effect. At that point, breast pumps should be covered with no issues.
Sorry that was so long, ladies, but I wanted to let you know how it works behind the scenes, so to speak. Hope I was able to help someone out!