Baby didn't move or kicked the whole night

Abana

My hubby's family, his mom and dad, along with his brother and sis-in-law stayed over for Christmas.
Sis-in-law is on her 3rd trimester. At around 2 am, we just got surprised when we heard them panicking and heading off to the nearest emergency room. My mom told me that sis-in-law's baby didn't move at all during the night... Turns out her baby is just fine.

Is this a regular occurrence? When I was pregnant I didn't quite experience this. But with a baby's movement just stopping, that's sure scary...