Table 1.

Summary of subgroup analyses for early-life BMI and breast and ovarian cancer risks.

Cancer site	Subgroups		Number of studies included	Summary RR (95% CI)	I2	P-heterogeneity
						Within subgroup	Between subgroups
Breast cancer	Tumour subtype	Oestrogen receptor-positive	5	0.75 (0.65, 0.87)	74.9%	0.003	0.29
		Oestrogen receptor-negative	3	0.60 (0.38, 0.98)	77.5%	0.01
	Age of BMI	BMI at age <18	7	0.87 (0.82, 0.91)	77.8%	<0.001	0.63
		BMI at age 18	10	0.79 (0.72, 0.87)	58.4%	0.01
		BMI at age >18	9	0.85 (0.79, 0.91)	38.9%	0.11
	BMI assessment method	Measured	6	0.86 (0.80, 0.93)	68.0%	0.008	0.49
		Self-reported	20	0.83 (0.79, 0.87)	60.4%	<0.001
	Region	USA	12	0.82 (0.78, 0.87)	59.1%	0.005	0.45
		Europe	10	0.86 (0.82, 0.90)	33.8%	0.14
		Other	4	0.81 (0.69, 0.96)	79.2%	0.002
Ovarian cancer	Region	USA	4	1.18 (1.05, 1.31)	0.0%	0.66	0.57
		Europe	3	1.11 (0.97, 1.27)	33.8%	0.22

This table shows the results from subgroup analyses by tumour subtype, age of BMI, BMI assessment method, and region.

BMI body mass index, CI confidence interval, RR relative risk.