Plus, some people just can't imagine a woman who doesn't want children. That's what we're for right? Our entire purpose in life. Most of that sentiment stems from religion, imo.
But for these folks, announcing you don't want children is akin to saying you don't want to do anything with your life; you don't want to fulfill God's purpose for your life. You're turning your back on God.
They can't wrap their heads around that.