Ovarian hyperstimulation syndrome is an exaggerated response to excess hormones. It usually occurs in women taking injectable hormone medications to stimulate the development of eggs in the ovaries. Ovarian hyperstimulation syndrome (OHSS) causes the ovaries to swell and become painful.
Mild ovarian stimulation involves the usage of lower doses of hormonal injections, generally in combination with oral tablets such as clomiphene/letrozole or tamoxifen. These combination results in reduction in the consumption of gonadotrophin .These are more patient friendly approach that reduces the incidence of hyperstimulation in patients known as hyper responders ( like PCOS) and also benefits patients with low ovarian reserve ( called poor responders) as the yield of eggs are similar whether one uses high or low doses in such patients. It is also cost effective and does not burden the patients especially when more IVF cycles are needed. These can also be used as an alternative to standard ovarian stimulation, in patients with normal reserve (normal responders), especially if one wants to reduce the cost of stimulation. However, the number of embryos available for freezing are lesser in mild stimulation compared to standard stimulation. Hence the cumulative pregnancy rates are lower with mild stimulation as compared to standard stimulation. In our unit we use this protocol either for severe PCOS (AMH> 5) or very poor ovarian reserve patients with age > 38 years , who have not responded to standard heavy stimulation and who want to try more IVF attempts using their own eggs .In these patients we give tab letrozole 5mg daily or tablet clomiphene citrate 100 mg daily for 5 days starting from Day 2 of the cycle . We add 300 to 450 units of hpHMG or Rec FSH daily from day 6 of cycle. Antagonist is added when leading follicle is > 14 mm in diameter. Double trigger(HCG + gnrh) is given when two leading follicles are > 17 mm and pick up is done after 35 hours .