Have a birthday in September, October, or November? Lucky you. You may have above-average chances of living an extra-long life.
In a recent study, researchers from the University of Chicago looked at data from more than 1,500 people who were born between 1880 and 1895 and who lived to be 100 or older. The researchers compared that data with the birth months and life spans of nearly 12,000 of the centenarians' siblings and spouses.
The majority of people who lived an extra-long life were born between September and November, the researchers reported in the Journal of Aging Research http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3236478/. Birthdays in March, May, and July produced 40 percent fewer centenarians.
The findings support a growing body of evidence that the conditions we experience extremely early in life may influence our health and survival many decades later, the researchers say. By comparing centenarians to their siblings, the study aimed to take into account living conditions early in life. By comparing spouses, the idea was to consider living conditions later in life.
The study didn't offer a definitive explanation for the birth and death patterns, though the researchers offered some theories.
It's possible, for example, that pregnant mothers had access to different levels of nutrition at different times of year in the late 1800s. Seasonal rates of infection may have also influenced fetuses in the womb, with vulnerability peaking during certain developmental periods.
Weather conditions at conception or birth could have an effect, as well. In the autumn in many parts of the United States, temperatures are neither too stressfully hot nor too stressfully cold. Several factors could combine to make fall babies especially hearty.
It's not clear how many of those conditions still apply today. But it's still worth recognizing that our early experiences may affect us long past birth, say the researchers.
This is the first study which found month-of-birth effects on longevity by using a within-family analysis, which proves that month-of-birth effects are real, and are not related to differences between families," said Leonid Garilov, an expert on aging, mortality, and longevity at the University of Chicago. "The findings of this study support the idea of early-life programming of human aging and longevity."
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