How safe and effective is sunlight for treating or preventing jaundice (yellowing of the skin, called hyperbilirubinemia) in newborns?
Babies with jaundice are often treated with phototherapy lamps, which emit blue-green light that alters the bilirubin (yellow substance found naturally in the baby's blood) so that it can be more easily excreted.
Sunlight emits light in a similar spectrum. However, sunlight also emits harmful ultraviolet rays and infrared radiation, which can cause sunburn and skin cancer. Further, exposing babies to sunlight might mean they could get too warm or too cold, depending on the climate.
In low- and middle-income countries (LMIC) phototherapy is not always available for babies who need it. Further, babies in these countries can be at increased risk for dangerous jaundice, where the bilirubin in their blood reaches levels that allow it to cross the blood-brain barrier and cause damage to the brain. Babies in LMIC are at increased risk for jaundice for a number of reasons, including poor access to maternal care during pregnancy, increased numbers of blood disorders causing jaundice, and increased risk of infection or birth trauma.
Given that sunlight is readily available, there is an urgent need to determine if sunlight is safe and effective at treating jaundice in babies in LMIC.
We included three clinical trials containing 1103 infants from two countries. The trials included infants born at or near their due date (35 weeks of gestation or later) who were less than two weeks old. One study evaluated healthy babies, and the other two evaluated babies with jaundice. In one study, the babies received either sunlight therapy or no treatment to assess sunlight for the prevention or reduction of jaundice. In the other two studies, infants with jaundice were randomly assigned to receive treatment with phototherapy machines or to receive sunlight through a light-filtering tent that blocked ultraviolet light and infrared radiation, and these groups were compared for improvement in their jaundice. One study did not comment on funding. The other two studies were funded by the Thrasher Research Fund. Evidence is current to June 2020.
Sunlight versus no treatment: babies exposed to sunlight may have a reduced occurrence of jaundice and be jaundiced for fewer days compared to babies who have no preventive treatment for jaundice. There was no reduction in readmission to hospital for jaundice in babies exposed to sunlight compared to babies who were not treated.
Sunlight versus other sources of phototherapy: when compared to babies who were exposed to electric phototherapy treatment, babies exposed to sunlight had a similar rate of decline in bilirubin levels. Using light-filtering films, babies exposed to sunlight did not have increased rates of sunburn, dehydration, or hypothermia. Babies exposed to sunlight were at an increased risk of hyperthermia. The effectiveness of sunlight might not be inferior to phototherapy, if sunlight can be delivered for at least four hours per day, and electric phototherapy can be delivered at night when needed.
Certainty of the evidence
The certainty of the evidence for outcomes in all three studies was very low to moderate. It was very low for all the main outcomes in each study. We are uncertain whether sunlight is effective for the prevention or treatment of hyperbilirubinemia in term or late preterm neonates.
Sunlight may be an effective adjunct to conventional phototherapy in LMIC settings, may allow for rotational use of limited phototherapy machines, and may be preferable to families as it can allow for increased bonding. Filtration of sunlight to block harmful ultraviolet light and frequent temperature checks for babies under sunlight may be warranted for safety. Sunlight may be effective in preventing hyperbilirubinemia in some cases, but these studies have not demonstrated that sunlight alone is effective for the treatment of hyperbilirubinemia given its sporadic availability and the low or very low certainty of the evidence in these studies.
Acute bilirubin encephalopathy (ABE) and the other serious complications of severe hyperbilirubinemia in the neonate occur far more frequently in low- and middle-income countries (LMIC). This is due to several factors that place babies in LMIC at greater risk for hyperbilirubinemia, including increased prevalence of hematologic disorders leading to hemolysis, increased sepsis, less prenatal or postnatal care, and a lack of resources to treat jaundiced babies. Hospitals and clinics face frequent shortages of functioning phototherapy machines and inconsistent access to electricity to run the machines. Sunlight has the potential to treat hyperbilirubinemia: it contains the wavelengths of light that are produced by phototherapy machines. However, it contains harmful ultraviolet light and infrared radiation, and prolonged exposure has the potential to lead to sunburn, skin damage, and hyperthermia or hypothermia.
To evaluate the efficacy of sunlight administered alone or with filtering or amplifying devices for the prevention and treatment of clinical jaundice or laboratory-diagnosed hyperbilirubinemia in term and late preterm neonates.
We used the standard search strategy of Cochrane Neonatal to search CENTRAL (2019, Issue 5), MEDLINE, Embase, and CINAHL on 2 May 2019. We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomized controlled trials (RCTs), quasi-RCTs, and cluster RCTs.
We updated the searches on 1 June 2020.
We included RCTs, quasi-RCTs, and cluster RCTs. We excluded crossover RCTs. Included studies must have evaluated sunlight (with or without filters or amplification) for the prevention and treatment of hyperbilirubinemia or jaundice in term or late preterm neonates. Neonates must have been enrolled in the study by one-week postnatal age.
We used standard methodologic procedures expected by Cochrane. We used the GRADE approach to assess the certainty of evidence. Our primary outcomes were: use of conventional phototherapy, treatment failure requiring exchange transfusion, ABE, chronic bilirubin encephalopathy, and death.
We included three RCTs (1103 infants). All three studies had small sample sizes, were unblinded, and were at high risk of bias. We planned to undertake four comparisons, but only found studies reporting on two.
Sunlight with or without filters or amplification compared to no treatment for the prevention and treatment of hyperbilirubinemia in term and late preterm neonates
One study of twice-daily sunlight exposure (30 to 60 minutes) compared to no treatment reported the incidence of jaundice may be reduced (risk ratio [RR] 0.61, 95% confidence interval [CI] 0.45 to 0.82; risk difference [RD] −0.14, 95% CI −0.22 to −0.06; number needed to treat for an additional beneficial outcome [NNTB] 7, 95% CI 5 to 17; 1 study, 482 infants; very low-certainty evidence) and the number of days that an infant was jaundiced may be reduced (mean difference [MD] −2.20 days, 95% CI −2.60 to −1.80; 1 study, 482 infants; very low-certainty evidence). There were no data on safety or potential harmful effects of the intervention. The study did not assess use of conventional phototherapy, treatment failure requiring exchange transfusion, ABE, and long-term consequences of hyperbilirubinemia. The study showed that sunlight therapy may reduce rehospitalization rates within seven days of discharge for treatment for hyperbilirubinemia, but the evidence was very uncertain (RR 0.55, 95% CI 0.27 to 1.11; RD −0.04, −0.08 to 0.01; 1 study, 482 infants; very low-certainty evidence).
Sunlight with or without filters or amplification compared to other sources of phototherapy for the treatment of hyperbilirubinemia in infants with confirmed hyperbilirubinemia
Two studies (621 infants) compared the effect of filtered-sunlight exposure to other sources of phototherapy in infants with confirmed hyperbilirubinemia. Filtered-sunlight phototherapy (FSPT) and conventional or intensive electric phototherapy led to a similar number of days of effective treatment (broadly defined as a minimal increase of total serum bilirubin in infants less than 72 hours old and a decrease in total serum bilirubin in infants more than 72 hours old on any day that at least four to five hours of sunlight therapy was available). There may be little or no difference in treatment failure requiring exchange transfusion (typical RR 1.00, 95% CI 0.06 to 15.73; typical RD 0.00, 95% CI −0.01 to 0.01; 2 studies, 621 infants; low-certainty evidence). One study reported ABE, and no infants developed this outcome (RR not estimable; RD 0.00, 95% CI −0.02 to 0.02; 1 study, 174 infants; low-certainty evidence). One study reported death as a reason for study withdrawal; no infants were withdrawn due to death (RR not estimable; typical RD 0.00, 95% CI −0.01 to 0.01; 1 study, 447 infants; low-certainty evidence). Neither study assessed long-term outcomes.
Possible harms: both studies showed a probable increased risk for hyperthermia (body temperature greater than 37.5 °C) with FSPT (typical RR 4.39, 95% CI 2.98 to 6.47; typical RD 0.30, 95% CI 0.23 to 0.36; number needed to treat for an additional harmful outcome [NNTH] 3, 95% CI 2 to 4; 2 studies, 621 infants; moderate-certainty evidence). There was probably no difference in hypothermia (body temperature less than 35.5 °C) (typical RR 1.06, 95% CI 0.55 to 2.03; typical RD 0.00, 95% CI −0.03 to 0.04; 2 studies, 621 infants; moderate-certainty evidence).