Hi Ashelen,
Thanks a lot for writing..My wife also 31W pregnant. Tile 4 days back we have observed a lot of movements. suddenly it stop moving since 4 days. We have consulted our doctor, gone for Color Doppler test. Report saying normal.
But still we could not understand why this much change in the movements happened in a day?
it may be normal, and they'll most likely suggest this: drink a glass of fruit juice, or something with sugar in it, and sit somewhere quietly and count how many movements you get in an hour. You're probably getting more than you think; when you're out and about and busy it's easy to miss movements. I think at 30 weeks it's 8-10 movements in an hour (and if you don't get that in a certain hour, try starting over with a new hour later in the day) but I'm NOT sure.....drink the sugary/fruit drink, count movements in an hour, then call your doctor and let them know the result, tell them "I drink {fruit juice} and counted {however many} movements in an hour. is this normal?". They may ask you to come in for an NST (non-stress test) to measure the baby's activity, or they may tell you it's normal. Good luck :)
(I just did some research online for you because I can't for the life of me remember how active my baby was at 30 weeks and most people say that their baby slowed down movements at 30 weeks, so you're probably right on track :) )
Oh hey I just found somethin cool for you :) http://medicalcenter.osu.edu/PatientEd/Materials/PDFDocs/women-in/pregnancy/fetal.pdf maybe that helps?