HIGH-ALTITUDE AND SPONTANEOUS PRETERM BIRTH

Objective: To study the association between high altitude and spontane ous preterm birth. Methods: Eleven placentas from cases of high altitu de (3000 m) spontaneous preterm deliveries with no clinical predisposi ng cause were collected in Abha, a city of southern Saudi Arabia. The placentas were examined histologically using sections stained by perio dic acid-Schiff and hematoxylin-eosin. The mean percentages of villi w ith syncytial knots and cytotrophoblastic cells were determined, Resul ts: Histology of the placenta samples showed an excessive formation of syncytial knots (45.4 +/- 13.3%) and cytotrophoblastic cells (52.7 +/ - 15.2%) at terminal villi. Conclusion: The enhanced formation of sync ytial knots and cytotrophoblastic cells is a histological feature of p lacental hypoxia, which may be secondary to maternal hypoxia resulting from high altitude hypoxia. Since placental hypoxia is associated wit h an increased incidence of spontaneous preterm birth, we suggest that high altitude may be involved in the etiology of spontaneous preterm birth.