Fetus or newborn affected by abnormal uterine contractions

**Definition:** Abnormal uterine contractions can either be hypertonic or hypotonic. Hypertonic contractions are ones that occur more frequently and are marked by an increase in resting tone to more than 15 mm Hg. Hypotonic contractions are ones where the number of contractions is unusually low, the resting tone of the uterus is less than 10 mm Hg, and the strength of contractions is consistently < 26 mm Hg.