How Can a Cheap Plastic Bag Save a Life?

(via ThinkAfricaPress, a riff on my original SciDevNet article)

Photograph by Arne Hoel/World Bank.

An everyday plastic bag – like the type you probably use to carry groceries – could help save the lives of some of the world’s most vulnerable newborns, according to a recent study in the Journal of Pediatrics.

Polyethelene bags are often used to temporarily keep extremely premature newborns warm immediately after birth in developed countries, but only for the few minutes before they can be placed in an incubator.

The study, conducted in 2011 at the University Teaching Hospital in Lusaka, Zambia, tested whether this approach would work for longer durations with moderately pre-term infants (between 26 and 36 weeks’ gestational age) in resource-constrained settings.

Here’s how it worked: pre-term infants were randomised at birth, with some placed in a polyethylene bag immediately after birth and others receiving normal thermoregulation techniques. Researchers checked the temperatures of the infants an hour later.

The results were stunning. Infants in plastic bags were 79% more likely to be an appropriate temperature than the control group – 59% and 33% respectively, an absolute difference of 26%.

Losing heat

Hypothermia, or having a low body temperature, is associated with increased morbidity and mortality in newborns. It’s a major risk for babies born in developing countries; while estimates vary significant, some studies show rates in newborns as high as 83%.

Hospitals in developing countries have few incubators or radiant warmers, which are expensive to procure and difficult to maintain. If a hospital does have one of these devices, there’s a decent chance it’ll be broken and inoperable.

But many women don’t deliver at the hospital, anyway. Sometimes, they prefer to give birth at home, and all too often, they are victims of geography and circumstance: a health facility may not be near enough to home, and if it is, it is often not qualified to provide emergency obstetric and newborn care.

“All babies are predisposed to hypothermia”, says Walderama Carlo, one of the authors of the study, in part because they “have a large surface area to body mass”. Basically, it’s easy for heat to escape, and once it does, infants have a difficult time producing more: they cannot immediately shiver. Their second line of defense, explains Carlo, is brown adipose tissue, or “brown fat,” which generates heat. But again, premature newborns don’t have enough of it.

Without these heat-generating mechanisms, infants cannot recoup the heat lost through evaporation, convection, conduction, and radiation. Once they are cold, they need outside warmth – either from the mother or an external device – to stay at the right temperature. The researchers believe that the plastic bag prevents evaporative cooling, keeping the baby warm for longer.

An extra pouch

In addition to reducing hypothermia, plastic bags can also help facilitate skin-to-skin contact (known as “Kangaroo Mother Care”), a World Health Organisation-recommended method to care for pre-term infants.

As Carlo noted, a main issue with KMC in sub-Saharan Africa is that “many mothers don’t do skin-to-skin because the babies void on them, or have a stool on the mother”. No mother wants to get pooped on.

“And we think that plastic bags, in some ways, may serve as a diaper in places where they don’t have diapers”, he continues.

Lisa Umphrey, a pediatrician with Medicine Sans Frontiers who has practiced in Uganda for five years, says that the study “suggests that the practice has importance in international, under-resourced settings”. She believes that, “Given the high rates of neonatal morbidity and mortality in these clinical settings, this is a topic that deserves much more discussion and investigation”.

As a first-line defense against hypothermia, food-grade plastic bags had a significant effect. Still, even babies put in the bags had a 41% chance of being too cold one hour after birth.

Other low-cost solutions such as the Embrace BabyWrap may help keep low birth weight babies warm longer. The device, an infant warmer optimised for hospitals with intermittent electricity and small budgets, is also used at University Teaching Hospital in Lusaka. Carlo says that it may be one “long-term solution for some patients”.

Ultimately, though, when it comes to cost, “there’s nothing as inexpensive as [plastic bags]” for hypothermia, says Carlo. “These are food-grade bags, [we can] just throw them away.”

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