A New Explanation For the Plight of Winter Babies

Ant passes along a Wall Street Journal report on research that turned up a new explanation for the lifelong challenges experienced by winter babies. "Children born in the winter months already have a few strikes against them. Study after study has shown that they test poorly, don't get as far in school, earn less, are less healthy, and don't live as long as children born at other times of year. Researchers have spent years documenting the effect and trying to understand it... A key assumption of much of that research is that the backgrounds of children born in the winter are the same as the backgrounds of children born at other times of the year. ... [Economist] Mr. Hungerman was doing research on sibling behavior when he noticed that children in the same families tend to be born at the same time of year. Meanwhile, Ms. Buckles was examining the economic factors that lead to multiple births, and coming across what looked like a relationship between mothers' education levels and when children were born." Here's a chart in which the effect — small but significant — jumps out unmistakeably.

Comments

School entrance age cutoffs, maybe?

[e9th]

The age cutoff for entry to kindergarten seems to cycle around mid-September, but varies quite a bit from state to state. But in general, a kid born in the winter will have to wait longer to start school.

Re:Jumps out?

[icebike]

From TFA:

The two economists examined birth-certificate data from the Centers for Disease Control and Prevention for 52 million children born between 1989 and 2001, which represents virtually all of the births in the U.S. during those years. The same pattern kept turning up: The percentage of children born to unwed mothers, teenage mothers and mothers who hadn't completed high school kept peaking in January every year. Over the 13-year period, for example, 13.2% of January births were to teen mothers, compared with 12% in May -- a small but statistically significant difference, they say.
--end-quote

So problem is more than adequately explained by being born to a teen mother, and winter birth need not be related at all.

Winter birth is probably attributable to spring break, and the re-emergence of summer fashions (read: skimpy) and horny young guys after a hard winter.

The real story is births to teen mothers burdens not only the mother, but also the baby. Winter has nothing to do with it.

Re:Jumps out?

[Rob the Bold]

Much more important is the lack of error bars, they are what you can use to decide if the difference is greater than noise. However since they seem to be confident enough to include a secondary maximum and minimum, we are led to assume that the error bars are rather small. Since TFA says the study looked at 52 million children over 12 years, it sounds fairly reasonable to suggest that error bars are relatively small w.r.t atleast the primary max an min.

TFA also says that the 52 million children in the sample were all of them, making the sample 100% of the population. That should result in some pretty small error bars, indeed!

The two economists examined birth-certificate data from the Centers for Disease Control and Prevention for 52 million children born between 1989 and 2001, which represents virtually all of the births in the U.S. during those years.