Impact of varying range of maternal oxygenation targets on fetal oxygenation and fetoplacental circulation in an ovine model of pregnancy

Pregnant women are highly susceptible to severe respiratory illness and ARDS, yet guidance on optimal maternal oxygen targets is limited. We investigated how varying maternal PaO₂ levels affect fetoplacental circulation and in-utero oxygenation. Using a large mammalian model of acute maternal hypoxia, we assessed whether maternal ARDSnet oxygenation targets (PaO₂ 55-80 mmHg, SpO₂ 88-95%) can be safely applied in pregnancy. Fetal carotid oxygen content decreased at maternal ARDSnet targets and when below PaO₂ 55 mmHg, with a non-significant trend toward reduced fetal cerebral oxygen delivery. Application of a maternal ARDSnet strategy may lead to suboptimal fetal oxygenation.