Decelerations
Early: peak coincides with peak of contraction; head compression during late 1st stage or active 2nd stage
Late: 20s lag between peak contraction and deceleration
Caused by acidosis, bleeding, infection, prolonged pregnancy, severe pre-eclampsia
Variable: varied timing, size, shape; caused by cord compression
Sinusoidal: undulating pattern, little/no variablilty; anaemia
