This is a good question actually, I never thought about whether or not a BH contraction would show on the monitor..
I agree with the other ladies who said BH would register on the machine. Also, Braxton Hicks are doing prep work for labor. They strengthen the uterus and help dilate and efface the cervix!
I had to be monitored the same way she did because my lil one wasn't moving as much. They also told me I was having contrations the entire time. I didn't even feel them They released me, so I guess everything was ok.
i had BH that registered but only hit maybe 20ish on the monitor, then when i was in actual labor they were hitting 90+. the nurse always told me to watch for 'waves' on the stip, those would be the ones that told me if labor was begining or already started.
When I went in because I got into a car accident I was having a lot of contractions that were registering on the monitor but I wasn't feeling them because they were just light BH ones. All the monitor measures is how hard your stomach is and for how long. I remember asking them about it and they described it like that. When I went in and had real contractions they were horribly painful and sky rocketing and coming back down dramatically.
BH register just like real ones so it just depends if they are random or coming the same amount of time apart.