In a natural cycle due to the control of the pituitary gland the ovary produces 1-2. eggs only. In order to remove the control of the pituitary and to eliminate the possibility of premature Lh surge , most of the cycle of IVF/ ICSI are down regulated. This is done with the use of gnrh agonist ie .Lupereloid / buserelin.

There are various ways of down regulating the most common method used is the long protocol . Here 5 cc of the Gnrh agonist in injected subcutaneously starting from day 20 of the previos cycle .The patient is also given progesterone tab 10mg daily for 5-7 days .Adequacy of the regulation is confirmed when LH is below 2, E2,below 20,and endrometrial thickness below 4mm. The other protocols using Gnrh analogues is the short where in theGnrh is added from the first day of menstrual flow.