Table 3.

Heterogeneity assessment.

	N	I2	P(%)	95 %CI
C-section
Location
China	14	79.35 %	0.88	0.73	0.98
USA	4	43.30 %	0.48	0.31	0.65
Europe	6	62.22 %	0.44	0.32	0.57
Sample size
Sample size of studies with pregnancy outcome < = 10	11	87.52 %	0.80	0.54	0.98
Sample size of studies with pregnancy outcome >10	14	83.12 %	0.66	0.51	0.80
Preterm
Location
China	14	46.99 %	0.20	0.12	0.30
USA	4	71.90 %	0.20	0.04	0.43
Europe	6	74.55%	0.24	0.12	0.39
Sample size
Sample size of studies with pregnancy outcome < = 10	10	70.12 %	0.33	0.15	0.54
Sample size of studies with pregnancy outcome >10	15	53.56 %	0.19	0.13	0.26
Adverse pregnancy events
Location
China	14	65.47 %	0.25	0.14	0.37
USA	4	80.69 %	0.26	0.05	0.54
Europe	6	77.96 %	0.25	0.12	0.41
Sample size
Sample size of studies with pregnancy outcome < = 10	10	78.23 %	0.39	0.17	0.64
Sample size of studies with pregnancy outcome >10	15	63.32 %	0.22	0.15	0.29
Low birth weight
Location
China	12	65.86 %	0.07	0.01	0.16
USA	2	NA	0.00	0.00	0.13
Europe	3	NA	0.02	0.00	0.15
Sample size
Sample size of studies with pregnancy outcome < = 10	9	76.18 %	0.14	0.01	0.36
Sample size of studies with pregnancy outcome >10	9	43.53 %	0.03	0.00	0.08

P: proportion; CI: confidence interval; I²: measures of heterogeneity across studies; NA: not applicable.