Telling the boss!

Alright ladies! So today is the day I get to tell my boss I'm pregnant! I just found out over the weekend, so I havent worked since I've known. I ha e to tell them due to safety precautions I'll have to take at work like not doing xrays. I work for a small vet clinic, we only have 3 full time techs (including myself) and 1 part time. Last year we had 5 full time.. and 3 of the girls got pregnant damn near the same time. The last one had her baby last November.. I'm afraid to see how my boss is going to take the news. Any suggestions on lightening the load when I tell him?