they hook you up to a fetal monitor that monitors heart rate and movement you get a little button every time you feel movement you hit the button. they then read over the printout and determine if the baby is under stress when he/she moves (if the heart rate is drastically diff). with my daughter they lasted about 30-45 mins, it really depends ( i believe) on how quickly he/she moves around that way they can get a good idea of how it is each time baby moves.
at 5:44 PM on Apr. 28, 2009