Every woman I know who is faced with fertility problems didn't "put off having children" for careers or anything else. It wasn't until later in life that they finally married and found someone who wanted to be a father.
I agree with you. I happen to know a lot of women who got married around 29-30ish and within 2-3 years started looking to have children and noticed they weren't getting pregnant - not everyone is in their 40's.