According to the research in the one of the issues of Gender & Society magazine, published by an assistant professor of sociology at Indiana University Youngjoo Cha, professions with average working hours posses more men and childless women, than working mothers.
As it turns out a lot of professions, which require more than 50 hours per week and mostly dominated by males, make working mothers to quit. Cha has also found that "having children increases overworking womens odds of exiting male-dominated occupations by 52 percent, as compared to their non-mother counterparts." The study shows that mothers who work full time tend to quit their jobs at a rate of 4.9%, while the ones who work more than 50 hours per week leave their jobs at a rate of 6.8%. (1)
Cha notices that: "When we compare the exit rate of full-time working mothers (4.9 percent) to that of their childless counterparts (4.5 percent), the differences are negligible. This suggests that motherhood status alone does not increase the exit rates; what drives womens exodus from male-dominated occupations are the joint effects of overwork and motherhood, which may reflect the greedy as well as gendered nature of family that demands disproportionately more hours from mothers.”(1)
As it turns out there is the perfect amount of hours that is suitable for working mothers in order for them to achieve their work and family balances, which is around 40 hours per week. The research also shows that unfortunately most working mothers have to quit their jobs, since it is too overwhelming for them to combine both family and work duties.