Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Menstrual blood loss
Systematic review	51 women Data from 1 RCT	Reduction in menstrual blood loss 6 cycles with progestogen-releasing IUD (levonorgestrel) with mefenamic acid Absolute results not reported	Reported as significant P value not reported	Effect size not calculated	progestogen-releasing IUD
Systematic review	30 women Data from 1 RCT	Menstrual blood loss with progestogen-releasing IUD (65 micrograms/day) with mefenamic acid Absolute results not reported	Between-group differences not assessed