Getting too much exposed to the sunlight can shorten life expectancy and impair fertility, says a new study.
Researchers from the Norwegian University of Science and Technology (NTNU) reached the conclusion after thoroughly studying lives of 9,000 people enlisted in church records. The 150-year data (1750 to 1900) included details about the exact age a woman first and last gave birth, gaps between her pregnancies, number of children, their marital status and reproductive health.
Facts from the records were compared with solar activity. UV radiation was determined by counting the number of sunspots each year had. It takes 11 years for these sunspots to reach maximum in numbers. Years with higher sunspots and increased solar activity is known to increase UV radiation on earth.
The data included details about rural women who worked in the fields and were more exposed to the sunlight.
Increased solar activity was associated with child mortality and reduced fertility in children. Children who were born in a year with a high solar activity died 5.2 years earlier than children born during less solar activity. These children showed less ability to reproduce and had fewer children than those who were not born during a high solar activity.
Exposure to the sun can help maintain levels of vitamin D, but at the same time, can also leave a negative impact on folate or vitamin B9, a vital nutrient needed for cell growth and development. A folate deficiency during pregnancy has been known to increase the risk of child mortality, according to Gine Roll Skjærvø and colleagues.
"There are probably many factors that come into play, but we have measured a long-term effect over generations. The conclusion of our study is that you should not sunbathe if you are pregnant and want to have a lot of grandchildren," Skjærvø said in a news release.
The study has been published in the Proceedings of the Royal Society B.
