Table 4.

Subgroup analyses for the association between childhood overweight/obesity and early puberty in girls.

Subgroup	No. of studies	OR (95% CI)	I2 (%)	P -value for heterogeneity	Test for subgroup differences
					χ2	P -value	I2 (%)
Geographic region					2.47	0.29	18.9
Europe	1	1.64 [0.58, 4.63]	–	–
Asia	5	3.23 [1.35, 7.76]	97	<0.001
North America	3	1.51 [1.04, 2.19]	70	0.04
Study design					7.56	0.006	86.8
Cohort	6	1.24 [1.08, 1.43]	62	0.02
Case-control	3	4.80 [1.85, 12.43]	92	<0.001
Sample size					37.64	<0.001	97.3
> 2,000	1	9.00[5.60, 14.46]	–	–
≤ 2,000	8	1.72[1.37, 2.17]	88	<0.001
Follow-up duration					5.21	0.02	80.8
> 8 years	1	1.79[1.20, 2.67]	–	–
≤ 8 years	5	1.12[1.08,1.16]	49	0.10
Age at enrolment					0.11	0.74	0
≥ 7 years old	4	1.54[0.96,2.45]	55	0.08
< 7 years old	2	1.39[0.93,2.06]	75	0.05
Type of exposure					1.71	0.19	41.4
Obesity	9	2.22 [1.65, 2.99]	94	<0.001
Overweight	3	4.67 [1.60, 13.63]	81	0.005
Definition of overweight/obesity					0.55	0.76	0
Body mass index	7	2.24 [1.63, 3.06]	95	<0.001
Skinfold thickness	1	3.00 [0.85, 10.54]	–	–
Body fat	1	1.64 [0.58, 4.63]	–	–
Definition of early puberty					49.26	<0.001	91.9
Age of menarche	5	2.28 [1.03, 5.04]	95	<0.001
Age of breast stage II stage	2	6.10 [2.18, 17.08]	61	0.11
Three criteria in the studya	1	1.18 [1.07, 1.30]	–	–
Age of each Tanner stage	1	5.94 [3.30, 10.70]	–	–
PDSb score > $\overline{x}$ + s	1	2.16 [1.56, 2.99]	–	–
Confounders controlled					8.09	0.004	87.6
None confounders controlled	3	4.87 [2.08, 11.39]	86	0.001
One or more confounders controlled	6	1.38 [1.15, 1.65]	80	<0.001

^a Earlier developers were girls who fulfilled at least two of the following three criteria: (1) highest tertile for estradiol; (2) tanner stage three for breast development; and (3) highest tertile for the puberty development scale (PDS).

^bPuberty development scale.