Outlier. You seem intelligent breh. I'm certain you have taken a statistics course.
I'm happy you found the wonder woman of post-natal women, but that is not the norm. Neither is it a fair expectation. The avg woman will struggle after just 3 children as their hormone and body composition changes dramatically with each child . Now imagine 5 of them, back-to-back.
And this is just the biological side. This doesn't take into consideration the logistics here. Keep in mind that this is 45 straight months where dieting is literally impossible at the detriment of upcoming children inside the womb and the detriment of ones currently being nursed.