Long work hours, part-time work, and trends in the gender gap in pay, the motherhood wage penalty, and the fatherhood wage premium

We assess how changes in the social organization and compensation of work hours over the last three decades are associated with changes in wage differentials among mothers, fathers, childless women, and childless men. We find that large differences between gender and parental status groups in long work hours (fifty or more per week), coupled with sharply rising hourly wages for long work hours, contributed to rising gender gaps in wages (especially among parents), motherhood wage penalties, and fatherhood wage premiums. Changes in the representation of these groups in part-time work, by contrast, is associated with a decline in the gender gap in wages among parents and in the motherhood wage penalty, but an increase in the fatherhood wage premium. These findings offer important clues into why gender and family wage differentials still persist.