Someone asking me to throw a party? Is that considered rude?

It sounds like your husband's friends are taking advantage of the situation. You know the phrase that if you give them an inch, they take a mile... it sounds like they've already taken about 50 yards to me. I would explain to him that you already planned a trip for his birthday and will not be throwing a party. Make it sound set in stone. Your husband said that it's okay to skip a party, so then it's skipped! Don't let his friends get plowed there anymore. You have a baby on the way and it's your right to raise them in a home where people aren't coming over and getting drunk all of the time. Everyone knows that when the baby comes, the partying is over. That's not to say that they can't come over and have a few beers, but they shouldn't be getting "plowed" there anymore. It's not a bachelor pad, you're married and having a baby! I would just stick up for myself and the baby and it sounds like your husband wouldn't fight you on it. You can tell his friends that they aren't welcome in your home if they're going to try to play games like that.