I told Blackwood I'd have the rest of my draft to him before Friday, but then I had to check into the hospital for a few hours on Thursday night. 30 weeks' gestation is not a time when you want to be having contractions every 5 minutes for 2 hours, so my doctor told me to go in to Labor and Delivery and have them keep an eye on me for a while. They gave me some medication that made me feel very nasty but stopped the contractions, and eventually sent me home on Pretend Bed Rest for a few days. This is not to be confused with Actual Bed Rest, which means you have to literally stay in bed all the time and can only get up to go to the bathroom. Pretend Bed Rest is more like "take it easy, don't lift anything heavy, sit or lie down when you can."
Blackwood was very understanding about the delay, especially when I told him that I had taken a book with me so I could work on my research while I was in the hospital (true story).
OK, it may not be the absolute BEST excuse ever; one of my friends once had a student miss class because his wife was getting a kidney transplant. But I still think "potential preterm labor" is at least a decent reason for taking an extra day on my draft. And, hey, I'm on Pretend Bed Rest for the weekend, which should give me plenty of time to work on my writing.