Table 1.

Variables in the choice of COS protocol

Factors determining individual patients' response to ovarian stimulation	Treatments used in ovarian stimulation protocols	Protocol variations
Demographics and anthropometrics (e.g., age, BMI and race)	Gonadotrophins: r-FSH/LH/hCG u-FSH/LH/hCG	GnRH agonist protocol (long, short and micro flare)
Genetic profile	GnRH analogues: Agonists Antagonists	GnRH antagonist protocol (standard, mild and modified natural)
Health status	Steroid hormones: Progesterone Oestradiol Testosterone DHEA	Agonist-antagonist protocol
Cause of subfertility	Other treatments: Aromatase inhibitors Growth hormone Clomiphene citrate	Natural cycles
Duration of subfertility
Nutrition

BMI = body mass index; COS = controlled ovarian stimulation; DHEA = dehydroepiandrosterone; GnRH = gonadotrophin releasing hormone; hCG = human chronic gonadotrophin; LH = luteinising hormone; r-FSH = recombinant follicle-stimulating hormone; u-FSH = urinary follicle-stimulating hormone.