Region of birth and lower levels of exposure to ultraviolet radiation during the first trimester of pregnancy were both independently associated with an increased risk of multiple sclerosis (MS) in adult life, shows research published in the BMJ.

The study was conducted across five states and one territory in Australia, among people born between 1920 and 1950 who were still alive at the time of the 1981 population census. A prevalence survey of MS had also been carried out in 1981.

There were 1524 patients with multiple sclerosis born in Australia 1920-50 from a total population of 2 468 779. Researchers analyzed their data by sex, month and year of birth and region of birth.

As expected, MS was more than twice as common among women as among men.

Overall, people born in November-December (first trimester in the Australian winter) had a third higher risk of subsequently developing MS than those born in May-June (first trimester in the summer).

When researchers analyzed their data by region of birth, they found that people born in regions with the lowest average levels of ambient ultraviolet radiation had a more than four times greater risk of subsequently developing MS than those born in the sunniest regions.

The association with month of birth was accounted for by the month- and region-specific ambient ultraviolet radiation during the first trimester – the effect of month of birth did not persist after adjustment for first trimester ultraviolet radiation.

The authors discuss the implications for prenatal care, and conclude: “Vitamin D supplementation for the prevention of multiple sclerosis might also need to be considered during in utero development.”

Source
PregnancyWeekly.com