Researchers from Norway conducted a study on increased ultraviolet (UV) radiation during the high sunlight years with maximum solar activity and its effect across generations.
Skjaervoe based his study on church records involving 9,000 people from 1750 to 1900 and used the information on the number of sunspots as an indication of the amount of UV radiation in a given year.
The sunspots reached a maximum every 11 years on average, which results in more UV radiation on Earth during years with high sunspot and solar activity.
UV radiation can reduce folate levels during pregnancy leading to higher child mortality though it can have positive effects on human vitamin D levels.
On an average, the lifespan of children born in years that had a great deal of solar activity was 5.2 years shorter than other children. The probability of dying during the first two years of life is very high, said researchers.
"There are probably many factors that come into play but we have measured a long-term effect over generations. The conclusion is that you should not sunbathe if you are pregnant and want to have a lot of grandchildren," said lead author Gine Roll Skjaervoe from the Norwegian University of Science and Technology.
The study also found that the lowest socio-economic state were most affected by UV radiation, especially women who worked in the fields with maximum exposure to the sun than other women, besides living on a poorer diet.