Table 5 Effects of study characteristics on the pooled OR values by subgroup analysis

Gestational hypertension

≤ 1000

-

-

-

P = 0.25, I² = 27%^a

5.57 (3.90, 7.94)

4

> 1000

-

-

-

P = 0.63, I² = 0%^a

1.53 (1.22, 1.91)

4

GDM

≤ 1000

-

-

-

P = 0.14, I² = 45%^a

4.17 (2.87, 6.08)

4

> 1000

-

-

-

P = 0.01, I² = 62%

1.43 (1.16, 1.77)

4

Caesarean section

-

Secondary

-

-

P = 0.03, I² = 58%

3.63 (2.85, 4.64)

6

-

Tertiary

-

-

P = 0.71, I² = 0%^a

1.69 (1.47, 1.94)

13

-

-

CC

-

P = 0.02, I² = 66%

3.72 (1.16, 4.96)

5

-

-

RC

-

P = 0.20, I² = 31%^a

1.78 (1.56, 2.03)

14

PROM

-

Secondary

-

-

P = 0.18, I² = 35%^a

8.48 (6.21, 11.56)

6

-

Tertiary

-

-

P < 0.01, I² = 61%

1.82 (1.57, 2.12)

13

-

-

CC

-

P = 0.13, I² = 46%^a

8.99 (6.27, 12.90)

5

-

-

RC

-

P = 0.03, I² = 57%

1.94 (1.68, 2.24)

14

-

-

-

1–4

P = 0.75, I² = 0%^a

5.02 (2.79, 9.03)

2

-

-

-

5–7

P < 0.01, I² = 83%

6.19 (4.77, 8.04)

5

-

-

-

≥ 8

P = 0.15, I² = 45%^a

1.78 (1.52, 2.09)

12