BEIJING, Sept. 5 (Xinhua) -- Chinese scientists have identified the genetic mechanism that allows Tibetans to maintain a high level of reproductive health in an oxygen-deficient highland environment.

Conducted by researchers from the Kunming Institute of Zoology (KIZ) under the Chinese Academy of Sciences, the study was published recently in the journal Current Biology.

According to the study, "The adaptation of Tibetans to high-altitude environments has been studied extensively. However, the direct assessment of evolutionary adaptation, i.e., the reproductive fitness of Tibetans and its genetic basis, remains elusive."

In order to identify a genetic basis for their good reproductive health at high altitudes, the researchers conducted systematic phenotyping and genome-wide association analysis of 2,252 mother-newborn pairs of indigenous Tibetans, covering 12 reproductive traits and 76 maternal physiological traits.

They found that, compared with the lowland immigrants living at high altitudes, indigenous Tibetans show better reproductive outcomes, reflected in their lower abortion rate, higher birth weight and better fetal development.

According to the study, the results of genome-wide association analyses indicate a polygenic adaptation of reproduction in Tibetans, attributed to the genomic backgrounds of both the mothers and the newborns.

"Collectively, these results shed new light on the phenotypic pattern and the genetic mechanism of human reproductive fitness in extreme environments," said He Yaoxi, the corresponding author of the study and a researcher at KIZ.

The study will provide important points of reference for highland medicine and physiology, He added.