Lingering grief associated with the death of a loved one has been hypothesized to precipitate acute health events among survivors on anniversary dates. We sought to study excess mortality risk in parents around the death date and birth date of a deceased child as an indication of a "bereavement effect". We conducted a population based follow-up study using Swedish registries including links between children and parents. All biological and Swedish-born parents who experienced the death of a minor child born were observed during the period 1973-2008 (n = 48,666). An increased mortality risk was found during the week of a child's death among mothers who lost a child aged 0-17 years (SMRR = 1.46, 95% CI 0.98-2.17). The association was stronger among mothers who lost a child aged 1-17 years (SMRR = 1.89, 95% CI 0.97-3.67) as compared to those who lost an infant (SMRR = 1.29, 95% CI 0.78-2.12). Cardiovascular diseases and suicides were overrepresented as causes of death in mothers who died around the anniversary. We found no significant increase in the mortality risk around the date of child's birth, nor any suggestion of excess mortality risk among fathers, but rather a depression of paternal death (SMRR = 0.60, 95% CI 0.34-1.03). Our study indicates an anniversary reaction among mothers who lost a young child. These results suggest that bereavement per se could have an effect on health and mortality which should be acknowledged by public health professionals working with bereaved people.