I have heard that you may have an energy boost before labor, however this was not the case for me with my first pregnancy at all (although I ended up being induced, but I was in early labor for about 2 days before hand, with painful contractions, but they weren't regular
)! I haven't heard anything about losing your energy, but hey, you never know!
I agree with Skyy--you should rest up as much as possible because you will probably be tired until your lo is about 3 months old... lol I didn't get anymore than about 5 hours sleep at a time with ds until he was about 6 months old because of breastfeeding, and I longed soooooo much for a solid 8 hours. It was well worth it though, and it will be this time around too (although I have a feeling I'll be MUCH more tired this time, with a 21 mo, and a newborn...)!