We study the consequences of actively raising children and simultaneously pursuing a career for mothers' health. Based on Swedish administrative data for the years 1990 to 2010, we document strongly increased old-age mortality rates among twin mothers compared to non-twin mothers. We use twins as an unplanned shock to fertility and proxy labor force attachment by stratifying the sample by education and pension income. Having twins substantially increases mortality---most strongly among highly educated mothers and those with above-median pension income. Deaths due to lung cancer, chronic obstructive pulmonary disease and heart attacks, which are associated with stress during life, are over-proportionally increased. These results are consistent with the existence of a double burden on mothers' health.