To Tell or Not to Tell?

My husband and I do not want to share that we are using a donor with anyone in either of our families.   I would love to hear how other women are handling this situation.

In fact, we aren't telling anyone about the IVF at all.  I do not want to be judged or to answer any questions, and I'm also concerned that my parents just wouldn't be able to understand any of it. 

Am I being dishonest by not telling everyone?  If I don't tell everyone, how do I tell the child?  And when?

Any thoughts or advice is appreciated. 

Thanks!