Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Menstrual blood loss
RCT	39 women with idiopathic menorrhagia	Percentage change in mean blood loss from baseline 12 months –68% with combined oral contraceptive (norethisterone acetate 1 mg) –83% with ethinylestradiol 20 micrograms with a progestogen-releasing IUD	P = 0.002	Effect size not calculated	progestogen-releasing IUD
RCT	112 women with idiopathic menorrhagia	Reduction in mean blood loss 34.9 mL with combined oral contraceptive (30 micrograms ethinylestradiol) 87.4 mL with 150 micrograms levonorgestrel with a progestogen-releasing IUD	P = 0.13		Not significant
RCT	112 women with idiopathic menorrhagia	Reduction in mean blood loss 2.5 mL with combined oral contraceptive (30 micrograms ethinylestradiol) 86.6 mL with 150 micrograms levonorgestrel with a progestogen-releasing IUD	P <0.01	Effect size not calculated	progestogen-releasing IUD