Emily Oster

2 min Read Emily Oster

Emily Oster

Does Birth Month Determine Success?

Q&A on the most desirable birthdays

Emily Oster

2 min Read

Does your birth month determine success? Is there any data to say that summer birthdays are more desirable than winter birthdays, or vice versa? Is September the best month because that’s when Beyoncé was born?

––September Baby

Or maybe December is the best birth month because that’s when Taylor Swift was born! Personally, I’m partial to March and April, since that’s when my kids arrived. But beyond personal feelings … your question is really about the data.

Broadly speaking, no, it doesn’t matter very much. I’ll give you a few things to think about, but I want to emphasize up front that all of the effects here are quite small and probably not worth worrying too much about. Also, it goes without saying that it isn’t as if you can perfectly time childbearing. My mom apparently tried to have both me and my brother over the two-week Christmas break period, in different years. She got closer with him than one might have thought (January 11), but you can’t really plan a due date.

baby opening arms and ready for a birthday
Paul Biñas / Unsplash

Two things do come out of the data, though. First: your child’s birthday will impact the age at which they start school. Most school districts in the U.S. have a September 1 cutoff for kindergarten, meaning a child with a summer birthday will be on the younger side in their class, and a child with an early-fall birthday will be on the older side. There are tradeoffs in both directions with this. Being the youngest in school can be tricky, especially for boys, which is why some parents will hold their children back a year in that case. On the other hand, if you do have the option to hold a kid back a year, a summer birthday may actually end up generating more flexibility.  

The second issue is illness. Babies who are born in the winter do tend to get more illnesses early on, so if you end up with a baby born in the November-to-January time range, it may make sense to consider whether you can hold them out of child care until they are a bit older and you’re out of respiratory season. 

Again, these considerations are both quite small. So I guess, when in doubt, aim for the Beyoncé timing.

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MEG
13 days ago

I think this question came from Malcom Gladwell’s book Outliers. He discusses how older kids born in the first half of the year tend to make more money and be better at sports. Another example was from hockey where all the star players had January to Match birthdays because the cutoff was Jan 1 so those kids were initially the biggest and then got more playing time and over the years the other kids never caught up.

Would be nice if this answer went a bit deeper into these.

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