Preemies' survival rates improve when the light is blocked from reaching the IV nutritional mixture they need, a Canadian review finds.

Researchers at the University of Montreal, Sainte-Justine Hospital in Montreal and the Children's and Women's Health Centre of BC in Vancouver have reviewed studies on parenteral nutrition — in this case, meaning it's delivered by IV — on about 800 preterm infants.

They were randomly assigned to receive light-exposed solution or light-shielded solution.

"Mortality in the light-protected group was half of that in the light-exposed group," Jean-Claude Lavoie of the University of Montreal and his co-authors reported in the Journal of Parenteral and Enteral Nutrition.

The last time there was a similar halving in mortality among preterm infants was about 20 years ago when researchers discovered infants need a surfactant in their lungs, Lavoie said.

The smallest infants — those born before 30 weeks of gestation — cannot eat by mouth because their digestive systems are too immature. Instead, they're fed intravenously with solutions of protein, fat, sugar and vitamins to support their growth and development. (Full-term pregnancy starts at 37 weeks.)

But when the solution is exposed to light, toxic or oxidizing molecules such as hydrogen peroxide are produced. A preemie's antioxidant defences aren't yet able to handle it.

"If we can reduce the peroxide then this is a winner," Lavoie said in an interview.

In the review of four studies, two from Vancouver, one from France and one from Egypt, the babies were born between 26 and 31 weeks of pregnancy. The mortality rates were studied at hospital discharge or the equivalent of 36 weeks of gestational age.

Currently, Lavoie believes no Canadian hospitals fully photo-shield parenteral solutions for preemies. The solutions need to be blocked from when they are prepared in the pharmacy to when they pass through bags, tubes and syringes and are received by the infants.

Protecting the nutrients from light could also prevent potential complications such as lung and kidney problems.

Lavoie's research team is working on a new way of delivering photo-protected solutions, which they hope will be low cost and easy for nurses to use.

The study's authors also suggested extending the research to the increasing number of children and adults receiving long-term parenteral nutrition at home to evaluate the effects of light protection on quality of life.

The review was funded by the Canadian Institutes of Health Research.