Mike: Hello, I'm Mike Clarke, podcast editor for the Cochrane Library. Some new-born babies will suffer from jaundice and there are several Cochrane reviews of possible ways to prevent or treat it. These were added to in July 2021 with a new review of the effects of sunlight. We asked the review's lead author, Delia Horn from the Larner College of Medicine at the University of Vermont in the USA, to tell us about the importance of this topic and the findings of the review.

Delia: Babies with jaundice, or to give it its more technical name, hyperbilirubinemia, have a raised level of a natural substance called bilirubin in their serum, which causes yellowing of the skin and can lead to serious illness. These babies are often treated with phototherapy lamps that alters the bilirubin so that it can be more easily excreted. The blue-green light from these lamps is similar to sunlight but sunlight also emits harmful ultraviolet rays and infrared radiation, which can cause sunburn and skin cancer. Exposing babies to sunlight might also mean they could get too warm or too cold, depending on the climate.
However, in low- and middle-income countries, phototherapy is not always available for babies who need it and babies in these countries are also more likely to develop complications from severe hyperbilirubinemia, where the bilirubin in their blood reaches levels that allow it to cross the blood-brain barrier and damage the brain. Therefore, it's important to know whether sunlight is safe and effective at preventing and treating hyperbilirubinemia in term and late preterm babies, and we did this review to try to find out. However, as I'll explain in this podcast, the currently available research still leaves us uncertain as to whether sunlight exposure is beneficial for infants who have, or are at risk for hyperbilirubinemia.
We identified three randomized trials involving just over 1100 infants. The overall quality of this evidence was moderate to very low, due to these being unblinded single-center studies with high risk of bias, indirectness, and imprecision. Two studies were performed in Nigeria and the third was from China. The Nigerian studies compared sunlight with conventional phototherapy for treating confirmed hyperbilirubinemia while the Chinese study looked at sunlight compared to no treatment for preventing it. Unfortunately, though, our main conclusion is that the evidence from these is not sufficient to determine whether or not sunlight is effective for either the prevention or treatment of hyperbilirubinemia in babies born late preterm or later.
Some of the studies also looked at other outcomes such as risk of hyperthermia, hypothermia, dehydration, sunburn, or re-hospitalization. This provided very low certainty evidence that sunlight may prevent the development of hyperbilirubinemia requiring hospitalization, but moderate quality evidence that there may be an increased risk of hyperthermia when using sunlight therapy.
In summary, our review shows that it's not possible to be certain if sunlight exposure is beneficial for babies who are at risk for hyperbilirubinemia or who already have it. Although sunlight may lower serum bilirubin levels at a similar rate to conventional phototherapy, we still need more research, some of which is ongoing, to investigate the effects more thoroughly and to find how best to implement and deliver this potential mode of therapy.

Mike : If you would like to learn more about the current evidence and watch for future updates of the review as new research becomes available, it's available at Cochrane Library dot com. Just go to the website and do a simple search for 'sunlight for babies'.