The uteroplacental circulation at high altitude: adaptation and maladaptation.

The greatest challenge of living at high altitude is hypoxia. Hypoxia imposes immense impacts on reproduction. Gestation at high altitude is associated with high incidence of fetal growth restriction (FGR) and pre-eclampsia owing to maladaptation of uteroplacental circulation/placenta insufficiency and oxygen delivery to the fetus. Both disorders have been replicated in animal models at low altitude by hypoxic exposure. Intriguingly, high-altitude natives such as Tibetans and Andeans are relatively protected from FGR. Hypoxia constitutes a severe insult to the uteroplacental circulation. In response to hypoxia, a range of dynamic responses occurs in uteroplacental cells/tissues. To offset detrimental effects imposed by hypoxia, uteroplacental cells/tissues also develop countermeasure mechanisms. The uteroplacental circulation adaptation to high altitude depends on whether a novel homeostasis is achieved.This article is part of the discussion meeting issue 'Pregnancy at high altitude: the challenge of hypoxia'.