Table 1 The characteristics of pregnant women, their pregnancies and neonates

Maternal characteristics

 Age (years)

29 (26–33)

30 (26–33)

31 (28–34)^**

 < 0.001

 Predelivery weight (kg)

64 (59–72)^**

68 (63–74)

74 (69–80)^**

 < 0.001

 Height (cm)

158 (155–160)^**

160 (157–163)

160 (158–164)^**

 < 0.001

 BMI

25.8 (23.6–28.7)^**

26.6 (24.8–28.9)

28.8 (26.6–30.7)^**

 < 0.001

 The number of pregnancy

2 (1–3)

2 (1–3)

2 (1–4)^**

0.014

 The number of delivery

0 (0–1)

0 (0–1)

1 (0–1)^*

0.004

Newborn information

 Baby gender

  Boy

85 (39.7%)^**

2520 (52.2%)

183 (71.5%)^**

 < 0.001

  Girl

129 (60.3%)

2308 (47.8%)

73 (28.5%)

 Gestational age at birth (weeks)

37 (37–38)^**

38 (37–39)

39 (39–40)^**

 < 0.001

 Premature infant (33–36 weeks)

45 (21.0%)^**

418 (8.7%)

1 (0.4%)^**

 < 0.001

 The birth weight of the baby

2355 (2195–2440)^**

3250 (2990–3510)

4160 (4070–4300)^**

 < 0.001

 Neonatal asphyxia

0 (0%)

15 (0.3%)

1 (0.4%)

0.921

The delivery information

 Scarred uterus

27 (12.6%)

756 (15.7%)

47 (18.4%)

0.233

 Caesarean section

90 (42.1%)^**

1362 (28.2%)

95 (37.1%)^**

 < 0.001

 Colpoperineal laceration

71 (33.1%)^**

2449 (50.8%)

102 (39.9%)^**

 < 0.001

  Grade I vaginal laceration

60 (28.0%)^*

1760 (36.5%)

58 (22.7%)^**

 < 0.001

  Grade II vaginal laceration

11 (5.1%)^**

689 (14.3%)

44 (17.2%)

 < 0.001

 Fetal distress in uterus

29 (13.6%)

554 (11.5%)

26 (10.2%)

0.511

 Low forceps delivery

5 (2.3%)

249 (5.2%)

18 (7.0%)

0.069

Diseases of pregnancy

 vaginal inflammation

25 (11.7%)

559 (11.6%)

36 (14.1%)

0.484

  Bacterial vaginosis

6 (2.8%)

111 (2.3%)

15 (5.9%)^**

 < 0.001

  Candida vaginosis

20 (9.3%)

310 (6.4%)

18 (7.0%)

0.229

  Streptococcus lactis vaginitis

2 (0.9%)^*

201 (4.2%)

14 (5.5%)

0.035

  Trichomonas vaginitis

1 (0.5%)

6 (0.1%)

1 (0.4%)

0.269

 Gestational diabetes mellitus

46 (21.5%)

1088 (22.5%)

86 (33.6%)^**

 < 0.001

 Hypertension

19 (8.9%)^**

189 (3.9%)

8 (3.1%)

 < 0.001

  Pregnancy hypertension

12 (5.6%)

168 (3.5%)

6 (2.3%)

0.148

  Chronic hypertension

7 (3.3%)^**

21 (0.4%)

2 (0.8%)

 < 0.001

 Placental hypofunction

30 (14.0%)

554 (11.5%)

22 (8.6%)

0.177

 Preeclampsia

29 (13.6%)^**

118 (2.4%)

7 (2.7%)

 < 0.001

  Mild preeclampsia

12 (5.6%)^**

81 (1.7%)

7 (2.7%)

 < 0.001

  Serious preeclampsia

17 (7.9%)^**

37 (0.8%)

0 (0%)

 < 0.001

 Intrahepatic cholestasis during pregnancy

8 (3.7%)

79 (1.6%)

2 (0.8%)

0.076

 Thyroid dysfunction

11 (5.1%)

411 (8.5%)

23 (9%)

0.368

 Virus infection

  HBV

5 (2.3%)

111 (2.3%)

6 (2.3%)

0.998

  Syphilis

1 (0.5%)

26 (0.5%)

1 (0.4%)

0.943

  HPV

0 (0%)

12 (0.2%)

1 (0.4%)

0.688

 Abnormal shape of placenta

19 (8.9%)

343 (7.1%)

18 (7.0%)

0.678

 Pelvic adhesion

3 (1.4%)

97 (2.0%)

6 (2.3%)

0.761

 Anemia

18 (8.4%)

562 (11.6%)

40 (15.6%)

0.048