Reproduction at High Altitudes

Abstract

Our concern with reproduction at high altitudes has arisen from an interest in placental oxygen transfer. The mammalian fetus, encased in a thick cyst of myometrium, establishes a chain of oxygen supply for its needs and persuades its mother to supply her end of that chain with quantities of well-oxygenated blood adequate for fetal development and survival. In contrast to other nutrients (amino acids, glucose, fats) which can be provided to the fetus in adequate amounts even if maternal blood flow is greatly reduced, oxygen transfer appears to be much more nearly flow-limited even at sea level (Guyton, 1963). One can hypothecate that the nutrient most critical for fetal (and species) survival in viviparous warm-blooded animals is oxygen because it is needed nearly continuously and in substantial quantities. How is the mammalian fetus provided with its needs for this element when its mother resides at high altitude where the primary problem, even for the air-breathing adult, is to obtain an adequate supply of oxygen in an environment with lowered atmospheric oxygen tension? Oxygen supply mechanisms to the fetus may be put under stress in such circumstances, and may fail. We propose to discuss the normal chain of oxygen supply to the mammalian fetus, modifications in the chain and its component links during maternal residence at altitudes from 10,000 to 15,000 feet above sea level, and evidence relevant to the subject of reproductive failure at high altitude.

Special Research Fellow in Medicine, supported by the National Institute Child Health and Human Development