I think there is also high risk OB & L&D which has many elements from both ER nursing (quick pace, sicker patients, more autonomy) as well as typical OB nursing (ya know, babies, women, all that good stuff). It does take a while and some experience to be able to get into that arena of nursing, and not all hospitals have high risk OB units, so your selection may be limited to larger hospitals!
Hope this helps a little!
I used to work in a town that had a women's only hospital that specaialized in L&D and high risk OB. This hospital had an ER and while anything could come through the ER it was designed to treat primarily OB/GYN related emergencies.
I currently work part time in an ER and am interviewing for a full time L&D position - i plan to just drop down to pool at the ER so i can pick up when i have off (if i get the L&D position). they are so simliar fieldsI think at one hospital you could try to do part time in both departments or like me, part time somewhere and full time or part time elsewhere... then you get to do both.