I was on labetalol for my entire 3rd pregancy including delivery & had no issues at delivery. But, during my 2nd pregnancy at delivery, not on labetalol or any BP meds, my daughter was in distress.
They had the internal monitors on her head because she had some big heart rate decels with contractions. I had only pushed one time & apparently she did not handle it well at all. I don't know what her heart rate was but it wasn't good. They called the OR to be ready just in case & called to have a crash cart delivered to my room.
My OB looked me square in the face & said quite emphatically "this baby has to come out NOW!" She said it so urgently that I got very scared & pushed with all I had & was able to get her out with that push (and an episiotomy). So at least with me it went south from one push/contraction to the next & it was because of baby's heart rate. If she hadn't come out right then I think they would have been wheeling me to the OR for a C-section. But, she came out before the crash cart even arrived & by the time they got her over to the warmer with a little oxygen she was fine. The NICU people arrived & said well I guess you don't need us here afterall. Whew! :)
So, I guess what I'm trying to say is that things *can* go wrong from one minute to the next. How far post partum are you? Can you talk to your OB about what happened? They would be the best source to find out what happened and why. Glad you are both doing so well now! :)