Table 2. Summary relative estimates for glioma in women.

	Exposure Categories			Heterogeneity
Risk factors	Highest(min to mix) vs. Lowest(minto mix)	Number of studies(Reference)	Pooled RR(95% CI)	PQ	I2	PEgger’s
OC	Ever vs. Never	6 (20–24, 41)	0.707(0.604–0.828)	0.806	0.0%	0.144
HRT	Ever vs. Never	6 (20–24, 29)	0.683(0.577–0.808)	0.744	0.0%	0.252
Menopausal status	Postmenopausal vs. Premenopausal	5 (23, 24, 27, 29, 42)	0.959(0.670–1.375)	0.031	62.4%	0.699
Parous status	Parous vs. nulliparous	6 (21, 22, 24, 25–27)	0.837(0.674–1.040)	0.005	69.9%	0.779
Age at menarche	Oldest (≥14) vs. Youngest(≤11 to ≤12)	6 (21–24, 27, 41)	1.401(1.052–1.865)	0.038	57.6%	0.076
Age at menopause	Oldest(≥50 to ≥53) vs. Youngest(≤40 to ≤50)	5 (21–24, 27)	0.972(0.782–1.209)	0.714	0.0%	0.093
Age at first birth	Oldest(≥30 to ≥35) vs. Youngest(≤20 to ≤25)	6 (21, 22, 24–27)	1.153(0.879–1.513)	0.105	45.1%	0.146