Objective: To investigate the effect of altitude on fetal birth weight
. Design: Crossectional randomized prospective study. Setting: Abha (3
,000 meters) and Mohayel (500 meters) cities in southern Saudi Arabia.
Subjects: Healthy pregnant Saudi women and their healthy newborn livi
ng permanently at the areas of study. Results: The mean birth weight w
as significantly greater at low altitude (3375 grams) than at high alt
itude (3207 grams) (P<0.001). The low birth weight observed at high al
titude may be attributed to intrauterine hypoxia to which the fetus is
subjected to. The intrauterine hypoxia appeared to be secondary to ma
ternal hypoxia resulting from high altitude environment.