Late-onset fetal cardiac decelerations associated with fetal breathing movements

While late decelerations are regarded as signs of fetal hypoxemia, fetal breathing movements (FBM) associated with late decelerations invariably have normal outcomes. Could late decelerations sometimes represent FBM?

Six patients between 37 and 42 weeks' gestation with 'late decelerations' associated with FBM (by ultrasound or tocodynamometer) during ante- or intrapartum monitoring were evaluated. Three were at high risk (diabetes, postdates, intrauterine growth restriction) and three were at low-risk.

'Late decelerations' arose in previously reassuring tracings. Oxygen or positional change had no effect. The decelerations were variable in length and shallow, and contained increased variability. Normal baseline rate and variability were maintained after the deceleration. Neonatal outcomes were normal.

'Late decelerations' as described are associated with normal outcome and may represent FBM. This understanding may reduce unnecessary interventions.