Sinusoidal antenatal fetal heart rate patterns.

The sinusoidal fetal heart rate pattern is significantly associated with severe fetal anaemia when seen in the antenatal period. Strict adherence to definition is important, as pseudosinusoidal patterns do not have the same grave prognostic significance. If this fetal heart rate pattern is seen antenatally it is our contention that the baby should be delivered urgently by Caesarean section, unless the fetal anaemia can be treated in utero.