Unpaid work done by women
Women do most of the work that is unpaid[@criadoperez2020Invisible women: exposing data bias in a world designed for men]. This is, cooking, cleaning the house, caring for children. Therefore, the statistics that show that women's health deteriorate at lower week-working-hours than men, is pointing towards the fact that women already work more hours and they also work for-pay somewhere else. This effect has consequences in many different metrics, industries, and countries.
Work policies designed for the average will be biased towards men.
These are the other notes that link to this one.