Can i get pregnant so soon after c section. Is it dangerous?

I had my baby four and a half weeks ago 35 weeks early. I had pre eclampsia so had to have him by c section. Last week me and boyfriend were messing around and had sex for a few mins then stopped. He did not ***. I know precum contains sperm but how likely am i to get pregnant so soon after having my baby and also is it very dangerous to be pregnant so soon after a c section?