The birthday effect (sometimes called the birthday blues, especially when referring specifically to suicide) is a statistical phenomenon where an individual’s likelihood of death appears to increase on or close to their birthday. The birthday effect has been seen in studies of general populations in England and Wales, Switzerland, Ukraine, and the United States, as well as in smaller populations such as Major League Baseball players.
Studies do not consistently show this effect; some studies find that men’s and women’s mortality rates diverge in the run-up to the birthday, while others find no significant gender effect. Suggested mechanisms for the effect include alcohol consumption, psychological stress relating to the birthday, increased suicide risk, terminally ill patients attempting to hold on until their birthday, an increased mortality salience, or a physiological cycle that causes the body to weaken annually. It has also been suggested that it may be a statistical artifact, perhaps as a result of anomalies in reporting, but the birthday effect has also been seen in studies that control for known reporting anomalies.