I'm pretty close with my families, so this may not best the best choice for you. But, when we decide to get pregnant again I plan to just tell them I'm trying.

Sure beats the heck out of fearing to tell them when you are pregnant and seriously emotional. this way it also doesn't come as a complete surprise and when you are preggers you will have a lot more genuine congratulations and a lot less 'oh Sh**!' from the parents