This paper documents that expansions of UK maternity pay in the 2000s improved children’s test scores while reducing maternal employment. Extending job protection alone generated similar employment effects but no detectable impact on children. None of these effects are recoverable with a conventional regression discontinuity (RD) design because eligibility is only imperfectly captured by the available data. We explain why existing corrections for measurement error in RD are not well suited and propose a simple imputation-based solution. The approach preserves RD’s main advantages—nonparametric identification and transparency—and remains valid when measurement error has economic content.