third women might forego higherpaying employment in favour of familyfriendly jobs that allow them to work fewer hours and spend more time at home on the other hand discrimination explanations are based on the notion that even though mothers may be equally productive employers may for strategic reasons pay them less than nonmothers and men of similar productivity in the labour market using longitudinal surveys from the united states waldfogel concludes that an unexplained motherhood wage penalty persists after controlling for human capital unobserved heterogeneity and parttime employment with a penalty for one child and a penalty for two or more children