Children whose mothers who do not get enough sunlight during their first trimester of pregnancy may be at higher risk of developing multiple sclerosis, according to a new study.

The study, published online in the British Medical Journal, surveyed more than 1500 people with multiple sclerosis who were born in Australia between 1920 and 1950 and identified patterns for the time of year they were born.

The researchers found that babies who were born in the summer, and thus their mother’s first trimester of was during the winter months with less sunlight, were more likely to develop multiple sclerosis.

The study found that babies born in November and December (summer months in Australia) were 32 percent more likely to develop multiple sclerosis than babies born in May and June (Australia’s winter).

The researchers believe that lack of exposure to sunlight, the main source of Vitamin D, during the first few months of pregnancy may affect how the fetus’s central nervous system or immune system develops.

The researchers also noted that the pattern they found mirrored previously reported patterns of multiple sclerosis in the northern hemisphere.