The cycle before your IVF treatment is scheduled, you may be put on birth control pills. This may seem backward -- aren't you trying to get pregnant? Actually, though, using birth control pills before a treatment cycle has been shown to decrease your risk of ovarian hyperstimulation syndrome and ovarian cysts and may even improve the odds of success.
Another possible option your doctor may ask you to look out for is going by your ovulation (either by basal body temperature charting or with an ovulation predictor kit). Let your doctor know as soon as you detect ovulation. Sometime after ovulation, the fertility clinic may then have you start taking a GnRH antagonist or a GnRH agonist, such as Lupron. This is so they can have complete control over ovulation once your treatment cycle begins.
Another possibility, if you rarely get cycles on your own, is taking progesterone, such as Provera, to bring on your period. In this case, your doctor will probably ask that you start taking the GnRH agonist or antagonist about six days or more after your first Provera pill. Again, though, this may vary. Always follow your doctor's instructions.