If women are statistically likely to need to take more time off work than men due to being a parent, then I would argue this is effectively a systemic pay gap. Whether or not that needs fixing is another question but it's totally bizarre to say "if you ignore all the reasons why women are often in positions where they receive less pay that men don't have to deal with, there isn't a gap".

(To be clear: whether or not this pay gap needs addressing is its own question entirely. It makes total sense to me that a woman needs time off to recover from giving birth or from health complications during pregnancy.)