Comparison 1. Oestrogen in combination with progestogen (sequential or continuous) versus placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Symptom scores	3	267	Std. Mean Difference (Fixed, 95% CI)	‐0.27 [‐0.47, ‐0.07]
1.1 E+P versus placebo	2	196	Std. Mean Difference (Fixed, 95% CI)	‐0.19 [‐0.40, 0.03]
1.2 E+P versus placebo +P	1	71	Std. Mean Difference (Fixed, 95% CI)	‐0.69 [‐1.18, ‐0.20]
2 Withdrawal due to adverse events	3	284	Risk Ratio (M‐H, Fixed, 95% CI)	0.64 [0.26, 1.58]
2.1 E+P versus placebo	2	244	Risk Ratio (M‐H, Fixed, 95% CI)	0.56 [0.19, 1.59]
2.2 E+P versus placebo +P	1	40	Risk Ratio (M‐H, Fixed, 95% CI)	1.0 [0.16, 6.42]
3 Specific adverse events (E+P versus placebo)	3		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
3.1 Bleeding problems	1	68	Risk Ratio (M‐H, Fixed, 95% CI)	0.53 [0.10, 2.70]
3.2 Breast tenderness	2	206	Risk Ratio (M‐H, Fixed, 95% CI)	1.64 [0.87, 3.11]
3.3 Headache	2	206	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.53, 1.57]
3.4 Nausea	2	206	Risk Ratio (M‐H, Fixed, 95% CI)	1.22 [0.55, 2.71]
3.5 Weight gain	1	68	Risk Ratio (M‐H, Fixed, 95% CI)	11.65 [0.67, 202.74]
3.6 Dysmenorrhoea	1	138	Risk Ratio (M‐H, Fixed, 95% CI)	1.55 [0.78, 3.05]
3.7 Skin irritation	1	40	Risk Ratio (M‐H, Fixed, 95% CI)	1.0 [0.39, 2.58]
3.8 Skin reactions	2	178	Risk Ratio (M‐H, Fixed, 95% CI)	0.56 [0.19, 1.59]
3.9 Skin pigmentation	1	40	Risk Ratio (M‐H, Fixed, 95% CI)	11.0 [0.65, 186.62]
4 Specific symptoms of PMS: psychological	2	119	Std. Mean Difference (Fixed, 95% CI)	‐0.79 [‐1.17, ‐0.40]
4.1 E+P versus placebo	1	48	Std. Mean Difference (Fixed, 95% CI)	‐0.33 [‐0.90, 0.24]
4.2 E+P versus placebo +P	1	71	Std. Mean Difference (Fixed, 95% CI)	‐1.18 [‐1.71, ‐0.65]
5 Specific symptoms of PMS: physical	2	119	Std. Mean Difference (Fixed, 95% CI)	‐0.60 [‐0.98, ‐0.22]
5.1 E+P versus placebo	1	48	Std. Mean Difference (Fixed, 95% CI)	‐0.29 [‐0.86, 0.28]
5.2 E+P versus placebo +P	1	71	Std. Mean Difference (Fixed, 95% CI)	‐0.85 [‐1.36, ‐0.34]
6 Quality of life (E+P versus placebo)	1		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
6.1 VAS for feeling unwell (change from baseline)	1	68	Mean Difference (IV, Fixed, 95% CI)	‐10.90 [‐22.60, 0.80]
6.2 General health questionnaire (change from baseline)	1	68	Mean Difference (IV, Fixed, 95% CI)	‐3.30 [‐9.98, 3.38]