I definitely would not hide it from your OB - that's what she's there for, to hear these things and know the possible causes or problems.
They're not going to jump to delivery any time soon unless it becomes dangerous for baby and you to remain pregnant. If you tell her, she can start watching you more closely, and recommend what tests to get done and whatnot.
Momma to R (11)
, Z (9)
, I (8)
, L (4)
, P (1)
& Apr '15
remembering Elliana Lucy (2.7.12)