Several studies found a significant motherhood penalty on wages and evaluations of workplace performance and competence even after statistically controlling for education, work experience, race, whether an individual works full- or part-time, and a broad range of other human capital and occupational variables. The OECD confirmed the existing literature, in which "a significant impact of children on women's pay is generally found in the United Kingdom and the United States." However, one study found a wage premium for women with very young children.