Who is expected to donate these sick days?
Are any women not done with children ever going to donate days? Because you might need those for your own pregnancies. And once you have kids, you need all of your sick days because your kids can't go to daycare or school when they're sick. If you're done raising kids, you're probably old enough for aging related illnesses, you'll need those days for managing care and prevention (colonoscopy for example). That leaves the younger single folks without children, who inevitably have fewer sick days to start. I never had any sick days when I was teaching part time, and no health insurance either.