No, I am not a girl who is able to answer the question with experience. I am able to provide the best recommendation possible for you, and that is to ask your physician straight up and honest because it is a fair and appropriate question for medicine to provide response.
OK, now that we have assured my incompetence, allow me to provide relevant insight to the effect of morphine on me when I recently had cervical fusion of multiple levels. A couple of stories because one is humorous and the other is as close to on point as I can provide.
During the pre-op testing an EKG was ordered. There were three nurses, a tech, and a physician in the tiny exam room with my wife and me. I had forgotten to turn off the SCS which allows me life renewed. Plumb forgot! The med people were about to wheel me off to the cardiac unit because they could not establish a rhythm for my heart. Of all things. Electricity will definitely interfere with electricity. As soon as I remembered my running SCS with a sheepish "do you suppose this might be interfering?" everything was returned to normal. We can laugh now, but the lesson was when having electrical testing performed shut off the stimulus.
Throughout the surgery, my SCS was shut down so as not to interfere with the electronics of any scanning device the team might use. Guess what..... in a status of shut down, the full effect of the morphine administered was really quite effective. Matter of fact, I remember N O T H I N G about even arriving in the Operating Room. Not one pea pickin little thing. First thing that came to me was awakening in my hospital room and my family had ordered something healthy for me to eat, such as soup. Soup.......
For our daughter in law last May when our grandson came, an epi was started, a mixture of morphine and lidocaine or something similar. It is a regional style pain block, and worked for her such that the process was workable for her. She has no SCS, but then, for all intents and purposes if yours is shut down for childbirth, your effect might be similar. The regional pain block may help as well with your chronic pain as baby makes his or her appearance.
For whatever it is worth, these are recent experiences of mine and of our daughter in law. AND Eva????? Samson is growing JUST fine!! I will have to upload photos...
Blessings and prayers pour over you as you approach surgery,
Then again as family life becomes part of your history,