Which condition does NOT negatively affect fetal oxygenation?

Maternal hyperventilation is characterized by an increase in respiratory rate and depth, leading to decreased levels of carbon dioxide (CO2) in the maternal blood. This condition can result in increased maternal blood pH, a state known as respiratory alkalosis. In certain circumstances, particularly in the absence of other complicating factors, maternal hyperventilation can improve fetal oxygenation by enhancing oxygen delivery to the fetus. This occurs because the increased oxygen content in maternal blood can facilitate greater fetal oxygen transfer across the placenta. Additionally, maternal hyperventilation can stimulate increased uterine perfusion, further benefiting fetal oxygen supply.

In contrast, the other listed conditions—decreased maternal cardiac output, placental abruption, and hypotension—can all significantly compromise fetal oxygenation. Decreased maternal cardiac output reduces blood flow to the placenta, which in turn decreases oxygen delivery to the fetus. Placental abruption can cause separation of the placenta from the uterine wall, leading to bleeding and reduced oxygen supply. Hypotension can impair perfusion to the placenta, adversely affecting the delivery of oxygen to the fetus. Hence, maternal hyperventilation stands apart as a condition that does not negatively impact fetal oxygenation.