Total (n = 500)

Mild (n = 380)

Severe (n = 120)

χ2

P

No.

%

No.

%

No.

%

1) Number of gestation

Singleton

430

86.0

332

87.4

98

81.7

Multiple

70

14.0

48

12.6

22

18.3

240.463

0.01

2) Liquor

Ok

421

84.2

379

99.7

42

35.0

287.295*

<0.001*

Oligohydramnios

79

15.8

1

0.3

78

65.0