Woman are taught the false dilemma fallacy. They are taught that children can wait while they build their career. For too many woman, it just ends up being the career and no children.
There is a time and place for everything. Careers can wait, until children have separated from the mother which happens naturally.
That's assuming they don't know. My point is that they do know, and they may say they didn't know because society is not willing to accept women saying "I'm done. No children for me." Career is the only excuse others in society will accept for a woman to not be actively working toward raising children.
Don't be surprised that children, male or female, who were traumatized within their own family growing up forgo families of their own. I know quite a few women, many who suffered through childhood trauma, who knew at a very young age that they didn't want to have children. Maybe it was a defense mechanism, maybe it's a deep distrust of the institution of marriage and the family, but they knew they wanted no part of it.
They're not fools chasing a career. "My career" is what they tell others in public. In private they'll share that they don't want children and every time they hear the "but children are...", "how could you not...", "everyone has issues...", it angers them because it denies what they've been through. These women found it better just to say, "Career now. Kids someday." to avoid conflict and judgement from intrusive outsiders.
Often, the worst flak they get are from other women who don't want to admit they didn't have the strength to not have children. The other women were afraid of being alone. They had children to "fix" their marriage. They hoped it would get better over time but it didn't, and now they have to live with guilt of screwing up their own kids.