High-altitude population neonatal and maternal phenotypes associated with birthweight protection.

BACKGROUND: States which reduce foetal oxygen delivery are associated with impaired intrauterine growth. Hypoxia results when barometric pressure falls with ascent to altitude, and with it the partial pressure of inspired oxygen ('hypobaric hypoxia'). birthweight is reduced when native lowlanders gestate at such high altitude (HA)-an effect mitigated in native (millennia) HA populations. Studying HA populations offer a route to explore the mechanisms by which hypoxia impacts foetal growth. METHODS: Between February 2017 and January 2019, we prospectively studied 316 pregnant women, in Leh, Ladakh (altitude 3524 m, where oxygen partial pressure is reduced by 1/3) and 101 pregnant women living in Delhi (low altitude, 216 m above sea level). RESULTS: Of Ladakhi HA newborns, 14% were small for gestational age (<10th birthweight centile) vs 19% of newborn at low altitude. At HA, increased maternal body mass index, age, and uterine artery (UtA) diameter were positively associated with growth >10th weight centile. CONCLUSIONS: This study showed that Ladakhi offspring birthweight is relatively spared from the expected adverse HA effects. Furthermore, maternal body composition and greater UtA size may be physiological HA adaptations and warrant further study, as they offer potential mechanisms to overcome hypoxia-related growth issues. IMPACT: Reduced foetal oxygen delivery seen in native lowlanders who gestate at HA causes foetal growth restriction-an effect thought to be mitigated in native HA populations. We found that greater maternal body mass and UtA diameter were associated with increased offspring birthweight in a (Ladakh) HA population. This supports a role for them as physiological mediators of adaptation and provides insights into potential mechanisms that may treat hypoxia-related growth issues.

Mini review of high altitude health problems in Ladakh.

Ladakh is a sparsely populated area of Indian Himalaya lying at 3-4500 m altitude mainly consisting of arid desert. This paper will discuss high altitude health problems in Ladakh under the following headings. 1. Acute altitude illness: acute mountain sickness (AMS), high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). 2. Effects of prolonged and permanent exposure to high altitude: (subacute and chronic mountain sickness). 3. Environmental dust and domestic fire pollution resulting in non-occupational pneumoconiosis and high prevalence of respiratory morbidity.

Silicosis in a Himalayan village population: role of environmental dust.

The Himalayan villages of Chuchot Shamma and Stok were surveyed because silicosis had been suspected from the radiographs of some of the inhabitants. The villages are agricultural, and Chuchot is exposed to frequent dust storms. Chest radiographs of villagers aged 50-62 were assessed blind by two independent observers using ILO criteria. In Chuchot five of seven men and all of the nine women examined showed varying grades of silicosis, compared with three of 13 men and seven of 11 women in Stok, which lies 300 metres higher and is exposed to fewer dust storms. The difference in prevalence of silicosis between the two villages was significant, as was the differences between men and women. Three patients from the village adjoining Chuchot were later found to have radiological evidence of progressive massive fibrosis. A necropsy on a man in a neighbouring village in the Indus valley showed classical silicosis in a hilar lymph node. Chemical analysis of the inorganic dust in the lung showed that 54.4% was elemental silicon [corrected]. This was similar to the silicon [corrected] content of dust samples collected from houses in Chuchot, which included particles of respirable size. X-ray microanalysis showed that quartz formed 16-21% of the inorganic lung dust. This study suggests that silicosis is common among the older inhabitants of these Himalayan villages. The dust exposure is clearly environmental and not industrial. Further studies are needed to define the extent and severity of silicosis in this community and to examine possible preventive measures.