You in school

This is you. Your in a highschool where no one in there has parents. Basically orphans. So, you were eating at the lunch table next to your alien boyfriend. Yes, your boyfriend is alien. He looks similar to human since his mother was alien and his dad was human. As you 2 were casually eating and talking with your friends, your and your boyfriends cheer ya'll to kiss. You guys said no at first but decided lets do it. So you guys did. But as soon as you guys pull away, your belly starts slowly growing until it looks 3 months pregnant. What is going on? You ask your boyfriend who is in shock.