Prediction of the Apgar Score from the Fetal Heart Rate Pattern

 

Features:

(1) baseline heart rate

(2) periodic changes

 

Heart Rate	Points
>= 200 beats/minute	3
180 - 199 beats/minute	2
160 - 179 beats per minute	1
101 - 159 beats per minute	0
80 - 100 beats per minute	1
70 - 79 beats per minute	2

 

where:

• The points in the original tables are negative values, not positive. However, the final point total will be subtracted from the maximum Apgar score of 10.

• Hon and Quilligan give a normal fetal heart rate as 120 - 160 beats per minute (page 783).

• No points are assigned in the tables for bradycardia < 70 beats per minute. In the implementation I assigned 3 points for this.

 

If the heart rate is:

(1) >= 160 beats per minute, AND

(2) the baseline is smooth

then add an additional 2 points.

 

Periodic Change	Finding	Points
cord compression	frequent (with >= 80% of uterine contractions)	1
	increasing	2
	< 80% of uterine contractions	0
uterine-placental insufficiency	present	2
	increasing	3
	absent	0

 

If

(1) cord compression is present, AND

(2) the heart rate is < 70 beats per minute

then add 1 point for each minute of bradycardia.

 

If

(1) uterine placental insufficiency is present, AND

(2) the fetal heart rate is < 100 beats/minute

then add 1 point for each episode.

 

If

(1) uterine placental insufficiency is present, AND

(2) the fetal heart rate is < 70 beats/minute

then add 1 point for each minute.

 

where:

• The original tables are somewhat ambiguous for assigning points to the periodic changes. I have used what I have interpreted the tables to mean.

• Cord compression pattern = periodic decelerations in the fetal heart rate of variable shape, which show no consistent relationship to the onset of uterine contractions (variable decelerations).

• Uterine-placental insufficiency = periodic symmetrical decelerations in fetal heart rate beginning characteristically well after the onset of uterine contractions (late decelerations).

 

points for fetal heart rate changes =

= (points for heart rate) + (points for smooth baseline) + (points for cord compression) + (points for uterine-placental insufficiency) + (points for additional periodic changes)

 

predicted Apgar score =

= MAX(0,10 - (points for fetal heart rate changes))