Back in my day, an LPN could work anywhere in the hospital including L&D. Back in the 1980s where I worked, there was a push for the LPNs who were working in specialty units (ER, critical care, L&D) to go get their RN and the hospital offered tuition reimbursement. At the time, they were told they would no longer have jobs in these places and would be reassigned to a regular floor if they chose to remain LPNs. In the end, they were allowed to remain LPNs and nobody was forced out. However, they were replaced with an RN when they retired or quit. Many LPNs took advantage of this opportunity, some chose to remain LPNs. If I recall, at the hospital where I worked, L&D had an LPN back in the early 2000s and when she retired, she was replaced by an RN. This was in a hospital and state where LPNs were used to the fullest extent of their training.
I would imagine that there are still LPNs out there in L&D but it is the exception to the rule. The LPNs who are still employed in L&D are probably veteran nurses who have been grandfathered in due to their experience and will be replaced by an RN when they retire.
If you wish to work in L&D your best bet is to go get your RN. However, it doesn't hurt to call up the nurse manager of the L&D unit to show your interest in such a position. It may be possible that they use LPNs in some capacity. At the very least, it may give you an advantage when it comes to finding an RN position.
Best to you,