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The imitation placenta that could save lives

128 36
18.07.2024

Artificial placentas and wombs could save the lives of premature babies, but what ethical considerations must be addressed before human trials begin?

It sounds like a plot straight out of a bad science fiction movie – human babies taken from their mothers' wombs and grown inside fluid-filled pods instead. Yet that is exactly what scientists at the Children's Hospital of Philadelphia (CHOP) in Pennsylvania in the US propose doing for infants at risk of extreme prematurity.

They are developing what they refer to as an "artificial womb", or extra-uterine environment for newborn development (Extend) to be precise. Extend is not intended to grow a foetus from conception to birth – that would be impossible even if it was desirable. Instead, it is intended to help boost the survival rate of extremely premature infants, who face a plethora of possible health effects throughout their lives.

A typical healthy pregnancy lasts around 40 weeks, with babies considered full term at 37 weeks. However sometimes complications occur in pregnancy that may result in a baby having to be delivered early.

Luckily, thanks to huge advances in neonatal medicine over the last few decades, most premature infants survive and are discharged with few complications. The most recent data shows that even 30% of 22-week-gestation patients survive if given intensive care.

"Honestly, 28 weekers and even 27 weekers do overall very well," says Stephanie Kukora, a neonatologist at Children's Mercy Hospital in Kansas City.

"It's really the babies born at 22 to 23 weeks that the outcomes are so severe that we are not sure whether the quality of life that they attain is acceptable."

Babies born on the cusp of viability often face severe health challenges. These infants weigh less than 2lb (900g) at birth, and critical organs such as the heart, the lungs, the digestive organs, and the brain are not yet developed enough to keep the baby alive without intensive medical care.

Short-term complications which frequently arise include necrotising enterocolitis (NEC), a serious illness in which tissues in the intestine (gut) become inflamed and start to die. Infants of this age are also very prone to infection and sepsis – a life-threatening drop in blood pressure that can damage the lungs, kidneys, liver and other organs.

Meanwhile long-term issues that can affect extremely premature babies include cerebral palsy, moderate to severe learning difficulties, vision and hearing problems, and asthma.

Even the very technology designed to save the babies' life – oxygen support and ventilation – can harm the infants' fragile lungs.

"At that early gestational age the lungs are still developing and should be filled with fluid," says George Mychaliska, a professor of surgery and obstetrics and gynaecology at Michigan University's C S Mott Children's Hospital.

"But when they're born very prematurely, we put an endotracheal tube in their trachea, and we force air and oxygen at high tension and pressure into their lungs – that is well documented to cause injury."

Over time the injuries lead to scarring of the lungs and a condition known as bronchopulmonary dysplasia, or chronic lung disease. Children often leave hospital needing long-term oxygen support and require mechanical ventilation for the rest of their lives. Ventilation can also raise the risk of retinal blindness. The blood vessels that feed the eye’s retina aren't fully formed until close to birth. Too much oxygen can trigger the growth of new, abnormal blood vessels, which can ultimately lead to retinal detachment.

The idea behind artificial wombs and placentas is to take the lungs out of the equation all together, allowing time for the foetus to continue developing in a safe environment until the baby is ready to take its........

© BBC


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