Babies born in April carry a far greater risk of suffering from neurological disease, like multiple sclerosis, experts said.
The researchers, based at Glasgow University and the city's Southern General Hospital, suggest mothers pregnant during the autumn and winter are less exposed to sunshine.
AdvertisementConsequently, the babies suffer from a shortage of vitamin D increasing the chances of the debilitating disease.
As part of the study, the Glasgow researchers examined data on about 1,300 MS patients born in the west of Scotland between 1922 and 1992.
It was noted that about 400 people born in March, April and May developed MS, which was 22per cent higher than expected.
And, almost half of all male and a quarter of female sufferers were born in April.
Meanwhile, those born in November had the lowest incidence of the disease.
"It's a very interesting observation and springtime seems to be a period of relatively high risk," the Telegraph quoted Dr Colin O'Leary of the institute of neurological sciences at the Southern General, as saying.
He added: "Seasonal risk may be a reflection of adverse events that occurred at the time of birth, in utero in the preceding nine months, or during the months following birth, when the central nervous system continues to undergo rapid development.
"There could be an association between reduced sun exposure and vitamin D levels."
Also, professor George Ebers, from Oxford University's department of clinical neurology at the John Radcliffe Hospital, said: "The difference [in developing MS in Scotland] between being born in April versus November is an astounding 50per cent.
"This is real, there's no doubt of a seasonal link. There are different theories, but I think the April excess of births could be linked to a sunlight deficiency.
"The focus is on trying to prove what the environmental effect is and, pending conclusive demonstration of that effect, some people might view it as prudent to conceive at certain times of the year to lower their child's MS risk if there is a history of the disease in the family."