Fetal heart rate monitoring-what are those squiggly lines anyways?

I am doing some research on fetal heart rate monitoring. For those who don't know what that means, that's the machine they hook you up to to look at your babies heart rate. I thought I'd organize my thoughts here. So, for those who want to know, here's the down and low on what those lines across the screen really tell us.

Basically when we look at the lines on the screen, we are trying to discern just how well oxygenated baby is. A normal tracing (that's what we call those lines), is between 120-160 beats per min. The beats vary between 6-25 each time. This is called moderate variability. There is also what is called accelerations, or a rise in the heart rate more than 15 beats per min longer than 15 sec, but less than 2 min. All these things indicate that the baby is receiving adequate oxygen.

FIGURE 1. Reassuring pattern. Baseline fetal heart rate is 130 to 140 beats per minute (bpm), preserved beat-to-beat and long-term variability. Accelerations last for 15 or more seconds above baseline and peak at 15 or more bpm. (Small square=10 seconds; large square=one minute)

Here's an image of a good normal tracing. Basically if you see these things, the baby is handling labor well. I'll go more into detail about the physiology behind it all in another post. For now, here's a good link I found if you are interested.

http://www.aafp.org/afp/990501ap/2487.html

References:

Obstetrics: Normal and Problem Pregnancies, 5th ed. Gabbe et al.

Fanaroff and Martin's Neonatal-Perinatal Medicine, 8th ed. Martin et al.