There are 3 categories of fetal heart rate tracing: Category 1,2, and 3
Definition of Category 1:
- Baseline rate of 110–160 beats/min
- moderate variability
- no late or variable decelerations
- early decelerations being present or absent
- accelerations being present or absent.
Category 1 tracings are reassuring.
A category 3 tracing is defined as:
- no baseline variability or
- the presence of recurrent late decelerations,
- variable decelerations,
- bradycardia, or
- a sinusoidal pattern
Category III FHR tracings are abnormal. Category III tracings are associated with abnormal fetal acid–base status at the time of observation. Category III FHR tracings require prompt evaluation. Depending on the clinical situation, efforts to expeditiously resolve the abnormal FHR pattern may include but are not limited to provision of maternal oxygen, change in maternal position, discontinuation of labor stimulation, treatment of maternal hypotension, and treatment of tachysystole with FHR changes.
If a Category III tracing does not resolve with these measures, delivery should be undertaken.
All tracings that are not category 1 or category 3 are considered category 2 tracings. The following algorith is for category 2 tracings.
Is there moderate variability OR are there accelerations?
This algorithm derives from the publication of Clark et al in AJOG 2013:
However, there are limits to trying to prevcent fetal acidosis with this algorithm: