If you have severe preeclampsia, you will probably need to be on magnesium sulfate while you have your baby and then for some time after the birth. Magnesium sulfate prevents preeclampsia from becoming eclampsia (seizures). You can have either a vaginal delivery or a c section on mag, but either way you will likely have a catheter and be confined to bed. "This is now a medical birth" was the phrase I heard a lot when I was in the hospital waiting to have LB.
I knew that mag would not be fun because the nurses looked really sorry for me when it was time to start the IV. Usually patients on mag get a big dose at the beginning and then a smaller dose for up to 48hrs. The big dose tends to be the worst part, and almost everyone feels very hot and vomits or dry heaves. My worst symptoms lasted about a half hour. Mag also causes muscle weakness, which meant that I was burning hot, and dry heaving while lying flat on my back (Badger was there holding a basin).
I know that Baby Center can be a terrible place, but this thread in the group for people with preeclampsia has a nice roundup of women's experiences on mag. At best, women report having very few symptoms, at worst they describe really vivid hallucinations. Nurses warned me that I would probably feel hot and vomit, but they didn't talk about the weakness, confusion, and visual problems that seem common with mag (or maybe they told me but I was too out of it to remember).
In my case, the best thing about mag (and the morphine cocktail I received) was that it made me feel very relaxed and unafraid. I had been very frightened of having a c section, but as they wheeled me into the OR and did the spinal I felt very calm. [I don't know what it's like to have a vaginal birth on mag. It doesn't seem like it would be pleasant, but women on the internets report that they got through it just fine. If you are planning a vaginal birth on mag, you might want to check out the peanut ball.]
After having LB, I stayed on mag for about another 24 hours. My most annoying issue was being unable to focus my eyes together and I ended up reading the Sunday Times with one eye closed so that I could focus. About 12hrs after LB's birth, I was able to go up and see her in the NICU even though I was still on mag. From hearing the stories of other women, I think it is unusual to be allowed to get out of bed so soon. I had to have a L&D nurse with me the whole time, so perhaps staffing and liability issues limit early trips to the NICU? If you know you are going to delivery on mag and your baby will be/might be going to the NICU, you should talk to your medical team about when you will be able to see your baby (and push them if it seems like it will be a long wait).
One final issue is bonding with your baby while you are still on mag. Some women report that they felt an immediate bond, while others do not. The first time I went to see LB, most of what I felt was fear. LB was intubated (had a breathing tube) so we had to hold her very carefully. She was handed over to me all bundled up and she looked so fragile and I felt very hot. The lighting in the NICU was very weird and I felt like I was having an out of body experience. At that moment, I really realized what a long road we had ahead, and I was so very afraid something terrible would happen to her. A day or two later, when I really got to hold LB, I felt an overwhelming amount of peace and love, but not on that first night. All that is to say, if you've given birth on mag, you've probably been worried about you baby and about your own health. You probably did not have the birth you imagined. You may be on a cocktail of drugs. None of those factors help you have a blissed out early experience with your baby. Many women who have been on mag, describe feeling emotionally distant or emotionally flat. It's not a great feeling, but it's a normal feeling. Give yourself a little time to recover from the birth and get off the mag. Even if you don't feel bonded with your baby immediately, it can come with time (and it will feel just as amazing).
[And my advice for c-section recovery, take your pain meds. If you are feeling significant pain you need more or different meds. I found that Percocet made me feel terrible and didn't control my pain well, but Dilaudid worked great. Also, use an abdominal binder during your recovery. It makes it easier to move around sooner, which helps recovery. I was given a big, industrial looking binder at the hospital, but you can also buy one through a medical supply store.]
My other preeclampsia awareness posts are here and here.