October: Overall health risk
While October doesn't stand out as having one particular disease associated with it, researchers found that an October birthday carries the most overall health risk. On the flip side, May was associated with the lowest overall health risk.
Incidence of ADHD spiked around those born in November, with Columbia's findings reflecting a similar study out of Sweden.
Respiratory disease, such as bronchiolitis, may be more common for people born in November. And for some reason, propensity for things like vomiting (September) and bruising (December) seems to be affected by birth month as well, as odd as that may sound.
Remember, diseases aren't 100% the zodiac's fault
Of course, it's extremely important to note that there are many, many different factors that result in developing such conditions, from genetics to environment to diet to exercise. You probably realize that people born in July get heart disease, and having a September birthday isn't an ironclad guarantee of asthma.
Whatever you do, don't blame your parents or the calendar too much, don't freak out that you're going to croak at any moment, and don't let this info stress you into an early grave. It's just a horoscope (albeit a science-y one), and as everyone knows, it doesn't always speak your truth.