Can circulatory fetal DNA be used to study placentation at high altitude?

Pregnancy at high altitude (>2700 m) is associated with higher rates of fetal growth restriction and preeclampsia as well as alterations in placentation, including increased villous vascularization and reduced remodeling of maternal spiral arteries. Because circulatory fetal DNA concentrations were shown to be enhanced in pregnancies affected by preeclampsia, we investigated whether similar elevations are also apparent in pregnancies at high altitude by examining ethnic Tibetans and recent migrant Han Chinese residents in Lhasa (altitude 3650 m) as well as Han Chinese residents in Guangzhou (altitude 7 m). Our data from this preliminary study (n = 10/study group) indicate that circulatory fetal DNA levels were significantly higher in the unremarkable pregnancies of Han women who moved to Tibet when compared to Han women at sea level. No significant difference could be discerned between migrant Han Chinese and ethnic Tibetans living in Lhasa. Our data, therefore, suggest that pregnancy at high altitude is associated with an increased liberation of cell-free fetal DNA and that no major ethnic differences are apparent.