This study of deaths from natural causes examined adult mortality around the birthday for two samples, totalling 2,745,149 people. Women are more likely to die in the week following their birthdays than in any other week of the year. In addition, the frequency of female deaths dips below normal just before the birthday. The results do not seem to be due to seasonal fluctuations, misreporting on the death certificate, deferment of life-threatening surgery, or behavioral changes associated with the birthday. At present, the best available explanation of these findings is that females are able to prolong life briefly until they have reached a positive, symbolically meaningful occasion. Thus, the birthday seems to function as a 'lifeline' for some females. In contrast, male mortality peaks shortly before the birthday, suggesting that the birthday functions as a 'deadline' for males.