Micturition and the Heart Period Cycle in the Human Fetus

Summary Campbell et al (1973) suggested that from 32 weeks gestation there was a cyclic filling and emptying of the fetal bladder, with a mean cycle length of 110 minutes. In the present study it was found that emptying of the bladder was associated with cyclic changes in fetal heart rate variation. In 95 per cent of the observations voiding occurred within 30 minutes after a change from a low to a high fetal heart rate variation episode. The possible relation of this association to fetal behavioural states is discussed.