In some extreme cases, a premature infant might need to be removed from the womb before completing the gestational period.
Doctors from The Children’s Hospital of Philadelphia in United States designed an innovative Biobag with the idea to allow premature newborns to continue developing in an artificial environment mimicking a mother’s womb.
The Biobag (Figure 1) used in the experiment is a clear plastic bag made of polyethylene, functions as a protection sac similar to how it is like in a mother's womb. It contains an electrolyte solution that mimics the amniotic fluid in the mother’s uterus where exchange of nutrients and waste takes place, facilitated by an external machine. "It is basically an artificial womb. What we tried to do is develop a system that mimics the environment of the womb as closely as possible," study leader Dr Alan Flake said.
Dr Alan Flake is the fetal surgeon at the hospital and lead author of the study. The study results were published in the journal Nature Communications in April. He said the purpose of developing an external womb is to produce life-sustaining conditions for infants who are born way earlier than normal gestation. The bag helps them continue developing important organs such as the lungs and brain.
Often, premature infants have health issues later in life due to incomplete organ development. For instance, their lungs are still immature enough to breath independently when they leave their mothers’ uterus. Current statistics show that 80% of babies born at 23 weeks of pregnancy and earlier do not survive. For the 20% kept alive in incubators, they could have significant health issues such as profound deafness and learning disabilities due to immature organs.
The human-sized lambs were chosen in the experiment because of the physiological similarity to humans. The lamb fetuses were removed from their mother’s womb via C-section and placed in the Biobags, filled with warm water and salts for 4 weeks. They were 4 to 6 weeks away from completing their normal gestational period of 21 weeks, which is equivalent to 23 or 24-week human gestation. The umbilical cords of the fetuses were connected to a machine outside the bag which functions as placenta, supplying nutrient-rich, oxygenated blood to the fetuses. The lamb’s heart did its own blood pumping for gaseous exchange to get fresh air and remove waste and carbon dioxide gas. Immersed in Biobag for 4 weeks, the lambs amazingly grew from tiny and pink fetuses to active, wool-coated small animals. Their lungs and brains developed; they could breathe and swallow, and were also able to wriggle their body and open their eyes.
Dr Flake said, “I think it’s just an amazing thing to sit there and watch the fetus on this support acting like it normally acts in the womb... It’s a really awe-inspiring endeavour to be able to continue normal gestation outside of the mom.” He added that the first-in-human trials might come after three years. In the meanwhile, they are monitoring the lambs who survived through the biobag experiment. In the future, this device could be used as a means to sustain the lives of preterm babies and help them to grow healthily.
Living in this era full of possibilities, we are likely to have a new device, an external man-made womb to help premature children survive in the future. There is risk of infection though, and finding the right amount of nutrients and hormones to support the development of a human baby outside the mother’s body can be challenging. Other scientists pointed out the need for further testing before the biobag can be evidently proved to be safe for use in human babies. The team hopes to use this artificial womb on extremely premature human infants aged 23 weeks to 28 gestational weeks to support normal fetal development and maturation and to increase their chances of survival.
Partridge, E. A. et al. An extra-uterine system to physiologically support the extreme premature lamb. Nat. Commun. 8, 15112 doi: 10.1038/ncomms15112 (2017).
(Available at https://www.nature.com/articles/ncomms15112)