- down reg is where they basically put your body into a drug induced menopausal state unsing synarel/lucrin before re awakening your ovaries using FSH injections. Advantage - more complete control over your hormone levels when stimulating as there is no natural hormone interference

- flare cycle is where they just stimulate your ovaries from minimal hormone levels following a natural visit from AF. Advantage - no down reg, so less drugs in your system. shorter process. also, some of us naturally don't respond to the FSH (puregon/gonal-f) injections after a down reg process, so this type of cycle allows for us to cycle!

- antagonist - very similar to flare cycle - except that, when you get to a certain point, you start having a second injection to stop you ovulating naturally before they are ready for this to happen. Advantages - same as flare cycle, except that they stop any natural production of LH (lutenising hormone) so has a more complete level of control over when ovulation occurs

hope that helps - i've put down my understanding of the cycles from what i've read - maybe someone else will come in and be a little more technical...

BG