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      We thank Drs Sahoo and Gulla for their commentary on our recent publication
      • Usuda H.
      • Watanabe S.
      • Saito M.
      • et al.
      Successful use of an artificial placenta to support extremely preterm ovine fetuses at the border of viability.
      that described the preclinical development of an artificial placenta for extremely preterm infants. As discussed in our submission, an abbreviated study period was selected because of a lack of performance data for extremely preterm fetuses that are supported via an artificial placenta-based platform; moreover, there are good data to show that a significant percentage of morbidity and death occurs acutely after extreme preterm birth,
      • Stoll B.J.
      • Hansen N.I.
      • Bell E.F.
      • et al.
      Neonatal outcomes of extremely preterm infants from the NICHD Neonatal Research Network.
      hence the duration of the studies undertaken. Drs Sahoo and Gulla are also quite correct to suggest, as we have done previously, that there are, of course, significant differences between ovine-based model systems and human beings.
      The correspondents raise several interesting points in relation to the use of therapeutic steroids and antimicrobial agents during this experiment, highlighting the potential risk of their application. Although we do not disagree with the need to proceed cautiously, it is important to assess the use of these agents against the current expected outcomes for extremely preterm infants using existing technology, which are more often than not extremely poor.
      • Stoll B.J.
      • Hansen N.I.
      • Bell E.F.
      • et al.
      Trends in care practices, morbidity, and mortality of extremely preterm neonates, 1993-2012.
      From an ethical standpoint, we agree that a robust conversation should take place well in advance of artificial placenta technology being adopted for use in the clinic. However, we do not share the same concerns as the correspondents regarding the potential for misuse of this platform. Given the profound improvements in preterm outcomes once 26–28 weeks gestation is achieved, it seems quite unlikely that an artificial placenta would be used across a wide range of gestational ages. Moreover, because the use of an artificial placenta requires catheterization of umbilical vasculature and a system with sufficiently low resistance so as not to compromise the fetal heart, it seems unlikely that fetuses much below 20 weeks gestation could be adapted to or maintained on an artificial placenta.
      Because, from a functional perspective, current artificial placenta-based systems essentially are limited to gas exchange and the delivery of nutrition and medication, it is not possible to use this technology to supplant the role of women in natural pregnancy. As is the case with current intensive neonatal care programs, the high-cost of using this technology similarly will do much to prevent its misuse. The question of legal status is indeed an interesting one; however, it does seem counterintuitive to introduce differential legal status and protections (relative to those currently conveyed to extremely preterm infants) simply on the basis of the application of an alternative means of providing gas exchange, nutrition, and medication.
      Last, we are in complete agreement that, based on current publicly available data, there are many more years of work necessary before clinical application of this technology should be considered. We are very much of the view that moves to introduce this technology to the clinic in the near future should be viewed as extremely premature.

      References

        • Usuda H.
        • Watanabe S.
        • Saito M.
        • et al.
        Successful use of an artificial placenta to support extremely preterm ovine fetuses at the border of viability.
        Am J Obstet Gynecol. 2019; 221: 69.e1-69.e17
        • Stoll B.J.
        • Hansen N.I.
        • Bell E.F.
        • et al.
        Neonatal outcomes of extremely preterm infants from the NICHD Neonatal Research Network.
        Pediatrics. 2010; 126: 443-456
        • Stoll B.J.
        • Hansen N.I.
        • Bell E.F.
        • et al.
        Trends in care practices, morbidity, and mortality of extremely preterm neonates, 1993-2012.
        JAMA. 2015; 314 (1039-5)

      Linked Article

      • Artificial placenta: Miles to go before I sleep…
        American Journal of Obstetrics & GynecologyVol. 221Issue 4
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          First of all, we would like to congratulate the authors for this adventurous novel piece of research.1 With advancement in technology and better medical care the survival of premature infants has improved drastically over the last few decades. However, the survival of micro preemies in the periviable period (22–25 weeks) and the associated long-term morbidities have not changed meaningfully. Hence, prevention of spontaneous prematurity is a real challenge and requires scientific breakthrough in the form of artificial placenta.
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