But "primary caregiver" is a loaded term that goes beyond biological necessity. What if a woman's husband is quitting his job to take care of the kid(s) and the woman plans to return to work? Is she the secondary caregiver because she spends less of her time doing childcare than her husband? What if the primary caregiver is a nanny?
Even if HR says "Oh, nevermind what you actually plan to do, if you're pushing the kid out, we can mark you as primary" it creates a terrible start to things if you have two parents who set out with good intentions to share childcare efforts equally. HR is telling one parent they're the "primary" and another parent they're the "secondary" and they have to sign legally binding documents attesting to this. It's just ridiculous. I think it's a great example of good intentions backfiring dramatically.