Contrary to earlier beliefs, infections common in childhood do not affect life expectancy later on in life, a new study has shown.

Earlier studies had suggested that inflammatory diseases in childhood, such as measles, smallpox and whooping cough increase the risk of cardiovascular diseases in adulthood, thus lowering life expectancy. The conclusion was based on the belief that life expectancy rose as a consequence of a child vaccinations.

In Finland, where the study was conducted, average life expectancy has gone from 35 to over 80 within the past 250 years.

The study shows, however, that there is no causal association between the two variables.

“Our study shows that childhood exposure to the infections did not cause a higher risk of premature death or reproductive problems,” Professor Virpi Lummaa from University of Turku said.

“We also didn’t find a link to cardiovascular diseases, strokes or cancer deaths.”

The study also shows no link between the childhood diseases and any of several aspects of reproductive performance, including lifetime reproductive success and age at first birth, in either males or females.

According to Lummaa, the increase in life expectancy is more likely due to health care received in adulthood and improved diet.

Researchers from the University of Turku in Finland and University of Stirling in Scotland collected data from 18th and 19th century Finnish populations experiencing varying mortality and fertility levels. The dates of birth, marriages and death were compared to the disease epidemics in the studied person’s hometown at the time of their childhood.

The researchers then analysed how long a person exposed to inflammatory diseases lived, whether they died from cardiovascular diseases and how many children they had.

The study was published in Proceedings of the National Academy of Sciences of the United States of America magazine.