Scientists at the university's hospital in northeastern Germany analysed several million deaths related to cardiovascular diseases between 1992 and 2007.
They found that women born in November lived some 7.3 months longer than those born in May, while men lived 11.7 months longer.
But the pattern was also similar for what the scientists called “all-cause deaths,” with a mean difference between subjects born in November and May at some 9.6 months for women of 9.4 months for men.
“Right now we can only speculate about the factors in the first months before or after our birth that have such a formative influence on cardiovascular risks,” project leader Thorsten Reffelman told news agency DAPD.
In addition to meteorological data or sun intensity, influences such as nutrition during pregnancy, air pollution or infectious diseases at different times of the year could be factors that also explain the data, he said.
Levels of physical activity tied to weather conditions may also explain the results.
In cooperation with statisticians, researchers found that the trend held for German states with both higher and lower life expectancies, and across rural and urban areas.
“Season of birth presents a well-defined variable associated with various environmental factors in early life, which are most likely not directly related to the genetic background,” according to the study published in this month's edition of the "Journal of the American College of Cardiology."
Other smaller studies have shown that factors such as adult arterial blood pressure and other cardiovascular issues were related to the birth month of patients, but the Greifswald researchers wanted to find out if this directly affected mortality too.
They suggested that subsequent studies focus on the underlying causes of this relationship.