Marianne Simonsen and Lars Skipper, "The Costs of Motherhood: An Analysis Using Matching Estimators", Journal of Applied Econometrics, Vol. 21, No. 7, 2006, pp. 919-934. The data used in this paper are the property of Statistics Denmark, who do not permit open access. Hence the data cannot be lodged here. The data are held at Statistics Denmark (Danmarks Statistik, Sejrøgade 11, 2100 København Ø, dst@dst.dk) to whom enquiries concerning access should be addressed. The study title under which the data are held is "Fertility and labour supply" project number 701869. SAS programs extracting the data are available under this project number, as are GAUSS computer codes used in the matching estimations. Marianne Simonsen msimonsen [AT] econ.au.dk Department of Economics, University of Aarhus