Ignorant people

I've been running into some acquaintances (using this term loosely), and when they see I'm pregnant, some of them have the nerve to ask if it was "planned" or an "oops". Well let's see; I'm in my 30's and married. How do people think this is an acceptable question? Really having trouble holding my tongue and usually just walk away. A mistake is spilling a glass of milk. A baby is a blessing (especially since a few doctors said the likelihood of us being able to have a baby was slim). Anybody else getting similar questions?