Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Haemoglobin concentration
RCT	39 women with idiopathic menorrhagia	Haemoglobin concentration 12 months 136 g/L with combined oral contraceptive (norethisterone acetate 1 mg) 134 g/L with ethinylestradiol 20 micrograms with a progestogen-releasing IUD	P = 0.71		Not significant