Imo, a MILF is usually over 30... I know that technically a mom is a mom, whether they're 18 or 40, but the term is usually used to describe an older woman. Like when a teenager thinks his friend's mom is hot, he says she's a MILF. Sometimes it's used to describe an older woman whether she has kids or not. I don't have children and choose not to, but I'm sure in 14 years when I'm 40, I'll still be called a MILF.