Goat fetuses disconnected from the placenta, but reconnected to an artificial placenta, display intermittent breathing movements.

To investigate whether placental factors are involved in the intermittent breathing movements in goat fetuses, we assessed electrocortical activity (ECoA) and tracheal pressure in 5 fetuses (124-135 days) separated from the placenta and connected for 48 h to an extrauterine fetal incubation system that provided umbilical arteriovenous extracorporeal membrane oxygenation. The fetal physiological condition on this system was almost the same as that in utero for at least 48 h after the preparation. All fetuses showed intermittent low-voltage ECoA and breathing movements. The breathing movements occurred almost exclusively during periods of low- voltage ECoA. The proportions of time spent in low-voltage ECoA and breathing movements were 48-57% and 46-56%, respectively. In conclusion, breathing movements of fetuses on the extrauterine incubation system were episodic, suggesting that intermittent breathing movements are intrinsic to fetuses, independent of placenta-derived factors.