From your source: "However, the only two groups who worked significantly less were new mothers, and teenagers working to support their families. New mothers sp

From your source: "However, the only two groups who worked significantly less were new mothers, and teenagers working to support their families. New mothers spent this time with their infant children, and working teenagers put significant additional time into their schooling" Note that 13% is likely the net value, so if this group slowed down, possibly other groups actually started working harder at the same time, compensating for some of the loss.