My friend has been TTC for 1.5 years for her second. She just got a bfp about 10 days ago!

Beta 1 - 273
Beta 2 - 4 days later 1735
Beta 3 - 2 days later 3470

Her progesterone is a 5.0.

She had an ultrasound and measured 5w 2d. Her doctor basically told her there is a 50% chance she will miscarry but didn't recommend progesterone supplements. Is that normal? Is it too late for progesterone? Should she get a second opinion?