Stopped gaining weight

Cassandra • Wife. Mom. Neuroscientist.
I'm 31+3 and have been gaining a pound a week since the beginning of 2nd trimester, without fail. But I haven't gained ANY in the past three weeks. I know the baby is supposed to be gaining a 1/2 lb per week from now on....
Any of you in the same boat and have talked to your OB/MW about it?