10.1 Positive feedback and childbirth

During childbirth, the pressure of the baby's head causes stretching of the uterus which stimulates uterine contractions, which causes further stretching, heightening the contractions and so the cycle continues until the foetus is expelled from the uterus (See Figure 15).

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Figure 15: Positive feedback loop in childbirth

Positive feedback is less common, which is understandable, as most changes to steady state pose a threat, and to enhance them would in most cases not be helpful.

© University of Dundee 2007