I've worked at both LDRP and L/D, mother baby hospitals. Every hospital is different. Most LDRP's require you to know labor and post partum because you usually keep your patient after delivery.
Other places have specific labor nurses, who transfer patients down the hall to the post partum section after recovery.
I've even worked in places that require you to be able to be the second nurse in NICU.
Call around to local hospitals, see how they're set up. But beware, by the time you're through with school things could change.
Around here, we went from L/D to LDRP and now are slowly going back to L/D.
Just keep an open mind. I started out in a OB/Gyne doctor's office as a reception, went to school, worked in the office, went to postpartum, snuck in a few deliveries and was hooked! I love all aspects of OB/Gyne, even the post-hysters that come to our floor.