The number of children under the age of 18 who are estimated to have experienced the death of a parent or co-residing grandparent caregiver in the United States surged to nearly three million by 2021, finds a new study involving UCL researchers. The research, published in Nature Medicine , is the first paper to examine trends in all types of orphanhood in the U.S. The authors combined multiple datasets that included state-level population and mortality estimates by sex, age, race and ethnicity;