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A few days after my older daughter was born, our pediatrician told me to place her bassinet in front of a window. She had a touch of jaundice, he said, but it was nothing to worry about: a bit of sunlight would take care of it.

He was right. But if I had known then what I know today about jaundice, I might have been more concerned.

Jaundice in newborns is caused by too much bilirubin — the yellow breakdown product of red blood cells, normally excreted in bile and urine. Common and relatively harmless, it can in some cases lead to more serious complications, including irreversible brain damage caused by the accumulation of bilirubin in parts of the brain.

This can cause seizures, cerebral palsy and, according to a series of reports by Danish researchers, an elevated risk of developmental disorders.

Working with the Danish Medical Birth Registry, the researchers looked at more than 700,000 children born in Denmark between 1994 and 2004. Close to five percent were diagnosed with jaundice in the weeks immediately following birth.

However, only the most severe cases were included in the registry. Those children, the researchers found, had an almost 90 percent higher risk than those without jaundice of being diagnosed with a developmental disorder, including (but not limited to) autism.

Within that group, children born at full term were most at risk, and the highest rates were in children born at 40 to 42 weeks of gestation. First-born children seem to be at a lower risk of an autism diagnosis.

Danish hospitals typically keep first-time mothers in the hospital for three to four days after delivery, the researchers note, which makes it more likely that jaundice will be diagnosed early, before bilirubin levels grow dangerously high.

The risk of an autism diagnosis also rises if the child is born between October and March — and disappears if a child is born between April and September. As I learned when I was a young mother, exposure to daylight helps lower bilirubin levels.

Children born in months with less exposure to daylight in the dark Danish winters have longer exposure to high bilirubin levels, which may explain why the risk of autism is higher for children born in the winter months.

This finding supports work by other researchers who have found links between autism and season of conception and birth.

As we slather ourselves with lotion to block out ultraviolet rays, it’s easy to forget that sunlight also heals and nourishes — and that treatment can be as simple as moving the baby closer to the light.