When people think about the costs of raising children, they generally include only the direct expenditure involved. However, there are other costs that are often ignored. These indirect costs refer to the loss of income that a household experiences because one or both parents spend time out of paid employment or take a lower paying job in order to look after the children. In this article, the authors report on a recent study which examines the impact of children on their mothers lifetime earnings - a hidden cost of raising children.