Your birth month can impact much more than your astrological sign according to a new study. In fact, it corresponds with the overall success of students throughout their childhood and adolescence.

A new working paper from the National Bureau of Economic Research says that the age of a child when they start school can make a considerable difference in their later cognitive development from ages 6 through 15, affecting not only their test scores, but college outcomes and the prospect of imprisonment for juvenile crimes.

So what does this have to do with your birth month?

The cut-off birth date between incoming classes in grade school in the majority of states in the U.S., including Washington D.C., is in September. This means that September babies are the ones who, for the most part, are the oldest students entering their classes each year.

The results of being the oldest in a group can be seen outside of the classroom too. In Canadian junior hockey leagues, the eligibility cutoff for each age class is January 1st, meaning that the players born in the beginning of the year are the oldest.

January babies go on to become the best hockey players in Canada. Forty percent of first-class hockey players in Canada were born between January and March, with more players born in January than all other months.

Being older by a few months may not seem like a big difference later in life, but at early ages when students enter kindergarten or start to play a sport, a few months may make a huge difference in where children are developmentally. This sets the oldest ones in the class or on the team up for early successes and additional attention from teachers and coaches, conclusively providing a boost.