If you want to play it nicely, you could always point out that DH will be home for 2 weeks to help, which means their visits would be more "helpful" after he returns. After all c-sections are rough, so having planned help for week 3 would be "just perfect".
But, I also don't think it's too rude to say "hey, my husband has that time off and we really want it to be just us and make the most of his time off, but we'd be happy to have you visit after x-date". Of course, my husband works 70 hour weeks and getting time off is like getting teeth pulled, so most of my family would immediately respect that.
Or you could be more proactive and just plan the dates your family will be visiting and pretend you never even considered them coming up that early. "Mom, so you'll be coming up around the 15th of February, right? I can't wait to see you."