Sherry - I think the letter is perfectly fine. I honestly don’t see how she can be offended at all! If anything, she will probably be relieved that she has something to refer to. Obviously, I don’t know your mother-in-law, but I really don’t see how offense could possibly be taken. Besides, deep down, do you really care if she is offended? Let’s face it, what is most important is your childs well-being -  better safe than sorry! Go for it! Hoping for a short labor for you.... :)!

ValerieD