Can you think of anything feminine that takes more strength than motherhood?
Sure. Enduring this kind of misogynistic classification of their womanhood when they don't have a child (regardless of the cause). The idea that someone isn't "feminine" or "strong" if they haven't pushed a child through their vagina† is complete and utter horseshit.
† Take note sometime of how much crap women who get c-sections will get from society.