Role of fetal deglutition and micturition in the production and turnover of amniotic fluid in the monkey.

In order to determine the precise role played by the absence of fetal swallowing or urine contribution in the disposal and production of amniotic fluid, we surgically occluded the fetal esophagus in 5 monkeys and the urethra in 2 monkeys. The amniotic fluid volume was then measured daily with an indicator dilution technic. Sham operations were performed on 3 monkeys of similar gestational age. It was found that in late pregnancy failure of fetal deglutition resulted in transient hydramnios which appeared to be followed by a readjustment in water exchange rates in other pathways by which the amniotic fluid volume returned to normal range. In midpregnancy fetal deglutition seems to have no appreciable effect upon the amniotic fluid volume. Diversion of fetal urine, however, appeared to result in a persistent decrease in the volume of the amniotic fluid.