I was put on crinone to boost my progesterone levels right after EPU, after the down reg cycle. The nurses told me that I would remain on it until my progesterone levels natrually came back. This could be anywhere up to 12 weeks when the placenta takes over the job.

From my limited understanding progesterone is what supports the pregnancy, which is why we get put on crinone.

my transfer was the 30 May - first few days 1 crinone then 2 crinone until yesterday (5 weeks) when they told me I could go down to 1 again until whenever.

Be aware of the side effects - I had cramping, which I thought meant AF was coming any second - it was just a side effect of the crinone and it has eased off a bit (thank goodness).

Good luck