Recently, the First Affiliated Hospital of Zhengzhou University (ZDYFY) announced a groundbreaking synthetic womb experiment without the use of extracorporeal membrane oxygenation (ECMO). In this experiment, a four-month-old fetal lamb survived for 90 minutes while hooked up to a unique apparatus, maintaining vital signs through a connection with its mother.
Zhao Gaofeng, the lead researcher and director of the pulmonary transplant surgery department at ZDYFY, highlighted this as China’s first ECMO-free synthetic womb experiment, signifying a major breakthrough—it suggests the potential for both males and females, given compatible blood types, to gestate fetuses.
The idea that anyone can bear children has sparked vast imagination. Discussions on social media ensued about factory assembly lines for babies as well as men getting pregnant and giving birth, at times overshadowing the technology itself.
Saving preemies was the original intent
The concept of ectogenesis was first introduced by biologist John Burdon Sanderson Haldane in the 1920s. Haldane envisioned a future where traditional instincts for reproduction would give way to a rational, external pregnancy process. He predicted that by 2074, less than 30% of babies would be naturally conceived and born.
Today, such ideas appear even more radical. For example, tech enthusiast and investor Sahil Lavingia once publicly responded to a tweet by Tesla CEO Elon Musk about population decline, suggesting that investments in technology like artificial wombs are essential to produce children faster, easier, and cheaper.
Research teams from the US, Australia, Japan, Israel, and other countries are also working on synthetic womb technology. Historically, efforts have included silicone membrane oxygenators and artificial amniotic fluid incubators. Despite advancements, global teams do not yet view synthetic wombs as viable replacements for pregnancy or devices that can fully replicate uterine functions. Instead, they are primarily seen as alternatives for neonatal intensive care.
Similarly, Zhao has emphasized that synthetic wombs are not intended for mass production of babies but to allow fetuses that cannot remain in the womb to continue living.
Treating premature infants remains a significant challenge both in China and internationally. Infants born before 37 weeks are considered premature, and those born before 28 weeks are extremely premature. Their treatment is complex and costly, often placing a heavy economic burden on families. With the recent increase in elderly mothers and the application of assisted reproductive technologies, the preterm birth rate could also rise.
For individual families, this also means a heavy economic burden. According to research data from Beijing Chunmiao Charity Foundation, over 85% of families with premature infants face hefty health expenditures, with treatment costs typically exceeding 40% of their ability to pay.
A doctor with decades of experience in reproductive medicine explained that major issues for premature infants include breathing and infections. In the womb, fetal lungs are filled with amniotic fluid, and oxygen is obtained from the placenta via the umbilical cord. Once born, a premature infant must breathe independently. Underdeveloped organs can result in unstable breathing and a higher risk of lung infections and bronchopulmonary dysplasia. Synthetic wombs could theoretically support better lung development.
In past experiments, artificial wombs have focused on simulating a maternal environment. For example, in a 2017 study, the Children’s Hospital of Philadelphia (CHOP) used a biobag to support preterm lambs equivalent to 23–24 weeks of human gestation, allowing them to survive for four weeks and develop normally.
Michigan Medicine (University of Michigan) used a similar approach, injecting a special liquid into the animal’s lungs and using extracorporeal circulation to oxygenate the blood. The university’s research showed that lambs survived for up to 16 days with promising development of the lungs and brain, transitioning to mechanical ventilation thereafter.
“If traditional neonatal intensive care provides higher-level life support, synthetic womb technology offers a simulated maternal environment for continued development, enhancing the chances of survival and healthy development of preterm infants,” the aforementioned doctor believes.
What does ECMO-free mean?
Currently, global leaders in synthetic womb technology are already moving toward commercialization and seeking venture capital. In September 2023, the US FDA even discussed the sanctioning of human trials.
In contrast, why did the ZDYFY team, who conducted its experiment on animals, attract so much attention?
This comes down to the concept of ECMO-free which was the highlight of the experiment, with some media outlets going as far as terming it the world’s first successful case of its kind.
Over the past few decades, breaking through the blood oxygenation problem has been a key milestone in synthetic womb technology, with ECMO playing a crucial role. ECMO allows for oxygenation of fetus blood after removal from the mother’s body, bypassing the heart and lungs, allowing these organs to rest and heal.
Although some scientists believe ECMO is not suitable for extremely premature infants, most improvement efforts have focused on the equipment. Initially, even the ZDYFY team used ECMO in experiments, describing it as crucial in the artificial womb system, akin to playing the role of the lungs.
36Kr learned that this is because ECMO does not involve any additional blood circulation, confining the circulation to the fetus.
In its recent results, although the team did not explain why this approach was abandoned, mentions were made of a different idea: replacing ECMO with a similar circulatory system by connecting the umbilical arteries and veins of the lamb to the mother’s neck arteries and veins. The team believes that the ECMO-free approach helps to avoid risks such as blood clots and infections, and eliminates the high costs of equipment maintenance.
Fu Shibo, a physician at a tertiary hospital in Shanghai and a medical science writer on Zhihu, explained to 36Kr that, although the specific connection method of ECMO-free was not clarified, it likely involves a “converter” with a structure similar to a dialysis membrane, establishing a blood flow link between the parent and the fetus, thus preventing the immune system from attacking the fetus as a foreign body while ensuring the exchange of gasses, nutrients, and metabolic waste across the membrane.
In terms of effects, the advantages and disadvantages of this experimental approach are relatively clear.
Firstly, there is a reduction in cost. Zhao mentioned in an interview with Chinese publication Health Times that the initial and daily operating costs of ECMO are RMB 60,000–70,000 (USD 8,381–9,778) and RMB 10,000–20,000 (USD 1,397–2,794), respectively. For a research team still in its early stages, the cost burden is substantial.
“The ECMO-free solution helps to reduce reliance on high-end overseas equipment and its associated consumables, especially in cases where there are no domestic alternatives for these consumables. Additionally, although not disclosed, the membrane structure device used in the ECMO-free solution is likely a self-developed device with independent IP rights, meaning the overall equipment cost would be lower,” Fu said.
Moreover, from the experimental design perspective, the ECMO in overseas teams’ solutions is only responsible for oxygenation. In other words, other nutrients must still be injected into the fetus’s blood. Comparatively, the Chinese team’s solution simultaneously addresses both gas and nutrient issues, making it simpler.
However, Fu added that the membrane structure device used in the ECMO-free solution cannot compare to the natural placenta in terms of blocking blood type antibodies, which might lead to neonatal hemolysis, thus imposing several limitations. For instance, the team itself mentioned that the fetal blood type must match that of the parent.
Awaiting the birth of a living lamb
Currently, a breakthrough in synthetic womb technology heading toward reality is the extended survival time of experimental animals.
In 2017, the maximum survival time of experimental lambs in CHOP’s biobag was four weeks. In 2023, Japanese scientists reported that six lantern sharks birthed using synthetic womb technology survived up to seven months.
In China, experimental lambs born from previous ECMO experiments by ZDYFY survived for seven days. With the latest ECMO-free solution, the animal survived 90 minutes. “The team indeed provided a new, equipment-reducing technological path. However, the earliest report of synthetic womb technology was in 2017, and Chinese scholars started relatively late, with shorter experimental observation times.” Fu believes this is a regrettable aspect of the ZDYFY team’s experiment.
However, none of the teams have yet delivered a living lamb that survived for a considerable period of time, challenging claims that animals birthed in artificial wombs can develop normally.
“This confuses me a bit,” Fu said. “If the experimental results show that the lamb’s systems develop normally, why not conduct longer observations, especially post-birth? Perhaps there are still inherent flaws that cannot be resolved, such as how to trigger the lamb’s first breath when removed from the amniotic fluid. If a cesarean section method was used to stimulate the lamb post-extraction, was it successful? None of this has been disclosed.”
Moreover, current research progress is largely still at the animal experiment stage. From a clinical perspective, doctors are most concerned about to what extent it can serve human premature infants who need it.
In September 2023, the US FDA held an independent advisory meeting to discuss how to better evaluate the safety and effectiveness of synthetic womb technology, such as the limitations of animal data and ethical difficulties of human trials. However, this discussion did not disclose specific human trial plans.
According to various media reports, the CHOP team has already submitted an application for human trials of the relevant equipment to the FDA. The Michigan Medicine team also hopes to advance to human clinical trials within 3–4 years. However, it is acknowledged that there remains fundamental gaps in understanding how human fetuses grow in synthetic wombs that need to be addressed before formal trials.
Ethics is also a concern for scientists. Some scholars have pointed out that surgeries involving extremely premature infants often occur early in pregnancy, with larger uterine incisions compared to full-term pregnancies, posing risks such as uterine rupture and abnormal placenta implantation, thus raising informed consent issues. “We worry that parents, after being informed of the child’s poor condition, might do anything, even if these technologies are completely untested and risky.”
KrASIA Connection features translated and adapted content that was originally published by 36Kr. This article was written by Hu Xiangyun for 36Kr.