Hypobaric hypoxia-induced intrauterine growth retardation.

2-week-pregnant New Zealand White rabbits were placed into a hypobaric chamber and maintained at 3,657 m (12,000 ft). Upon delivery (31 +/- 1 days) or at cesarean section (on day 30), all newborns were sacrificed and organ weights were compared to those of control pups maintained at 128 m (420 ft). Significant findings in the hypobaric animals included a diminished birth weight, placental weight, and liver weight per body weight. Placental weight per body weight was similar in both groups. The brain weight per body weight, brain to liver ratio, and right ventricle to left ventricle plus intraventricular septal weight ratio were significantly increased in the hypobaric pups.