A survey of more than half a million men in Austria has found that if you are born in March, you will be slightly, but significantly, taller than someone born in September.
Though the variation is just 0.6 centimetres (0.2 inches) between the peak and trough, with the average occurring for babies born in January and July, a team at the Institute of Human Biology at the University of Vienna is confident that the link exists.
They suggest that the differences, which were observed over 10 years in army conscripts aged 18, could be caused by the pineal gland, located in the brain, which produces the hormone melatonin in reaction to the daily cycle of light and darkness.
"The underlying mechanism [of height differences] might involve the light- dependent activity of the pineal gland," said Gerhard Weber, who led the team which reports today in the science journal Nature.
However the link arises, it has a peculiar periodicity: the body heights vary exactly with the amount of sunshine, in a 365-day cycle, but the tallest babies are born 89 days ahead of the longest day (or possibly, the researchers suggest, 276 days after it). "This may provide empirical facts for clinical research on the pineal gland and melatonin," they say. Or it may just be another line for astrologers: "If you are born today ... good news! You have a slightly better chance of becoming a supermodel."