You could make a fair argument along that line if you measured the cost. Just having the baby means a few weeks off at most since there's nothing gender-specific about childcare, average person has about two babies, a couple months out of decades of work, you could reasonably argue that women should make about a quarter of a percent less than men.

My point is, don't bring up a flawed argument that's used to support unfair discrimination to attack another argument. That's nothing more than a strawman.