When and how do you break your pregnancy news to your boss?

After the first trimester, for sure. Make sure to tell her on a day that's not too hectic. Schedule a chat in advance so your boss can make room for you on their sched. Don't forget to prepare answers to certain questions such as when you plan to go on maternity leave, or how you plan to get certain deliverables in ahead of time. This will help you have a hassle-free maternity leave.