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Table 2 Obstetric characteristics of the participants in the study according to their pre-pregnancy body mass index (BMI)

From: Pre-pregnancy Body Mass Index (BMI) and delivery outcomes in a Canadian population

Obstetrics characteristic

Total sample (N = 1996) 1

Normal weight (BMI 18.5-24.9 kg/m 2)

Overweight (BMI 25–29.9 kg/m 2)

p*

Obese (BMI ≥ 30 kg/m 2)

p †

Gravidity

   

0.488

 

0.142

  Primigravida

774 (38.9)

522 (39.9)

179 (38.1)

 

73 (34.6)

 

  Multigravida

1215 (61.1)

786 (60.1)

291 (61.9)

 

138 (65.4)

 

Parity

   

0.416

 

0.348

  Primiparous

1045 (52.4)

699 (52.3)

241 (51.1)

 

105 (49.8)

 

  Multiparous

951 (47.6)

614 (46.8)

231 (48.9)

 

106 (50.2)

 

Assisted conception2

   

0.125

 

0.395

  No

1864 (97.1)

1234 (94.3)

435 (92.4)

 

195 (92.9)

 

  Yes

58 (2.9)

74 (5.7)

36 (7.6)

 

15 (7.1)

 

Gestational age at delivery

   

0.744

 

0.422

  370/7 – 416/7 weeks (term)

1991 (99.7)

1309 (99.7)

471 (99.8)

 

211 (100)

 

  ≥ 420/7 weeks (post-term)

5 (0.3)

4 (0.3)

1 (0.2)

 

0 (0.0)

 

Type of labour

   

<0.001

 

<0.001

  Spontaneous

1285 (66.6)

904 (71.2)

277 (60.7)

 

104 (51.0)

 

  Induced

644 (33.4)

365 (28.8)

179 (39.3)

 

100 (49.0)

 

Method of induction3

 Oxytocin

   

0.100

 

0.197

  No

138 (21.4)

88 (24.1)

32 (17.9)

 

18 (18.0)

 

  Yes

506 (78.6)

277 (75.9)

147 (82.1)

 

82 (82.0)

 

 Amniotomy

   

0.630

 

0.596

  No

392 (60.9)

226 (61.9)

107 (59.8)

 

59 (59.0)

 

  Yes

252 (39.1)

139 (38.1)

72 (40.2)

 

41 (41.0)

 

 Other methods4

   

0.485

 

0.605

  No

504 (78.3)

287 (78.6)

136 (76.0)

 

81 (81.0)

 

  Yes

140 (21.7)

78 (21.4)

43 (24.0)

 

19 (19.0)

 

Mode of delivery

   

0.236

 

<0.001

  Spontaneous vaginal delivery

1492 (77.3)

998 (78.6)

341 (74.8)

 

153 (75.0)

 

  Operative vaginal delivery

192 (10.0)

129 (10.2)

55 (12.1)

 

8 (3.9)

 

  Caesarean section

245 (12.7)

142 (11.2)

60 (13.2)

 

43 (21.1)

 

Labour duration in spontaneous vaginal deliveries

  Second stage of labour (min)

64.4 (68.6)

66.1 (61.7-70.5)

62.6 (55.8-69.3)

1.000

57.7 (47.6-67.8)

0.448

  Third stage of labour (min)

7.7 (9.2)

7.81 (7.2-8.4)

7.6 (6.8-8.4)

1.000

7.1 (5.8-8.3)

1.000

Labour duration in operative vaginal deliveries

  Second stage of labour (min)

115.8 (87.7)

116.6 (100.4-132.7)

108.2 (88.2-128.2)

1.000

157.3 (88.7-225.7)

0.614

  Third stage of labour (min)

6.1 (6.5)

6.35 (5.1-7.6)

5.89 (4.7-7.1)

1.000

4.0 (2.7-5.2)

0.983

Obstetrical analgesia (epidural)

   

0.017

 

<0.001

  No

752 (39.0)

532 (41.9)

162 (35.5)

 

58 (28.4)

 

  Yes

1177 (61.0)

737 (58.1)

294 (64.5)

 

146 (71.6)

 
  1. Data presented as n (%) (χ2 test) for categorical variables or mean (95% confidence intervals) (analysis of variance ANOVA) for continuous variables.
  2. 1May not add to total number (N = 1996) due to missing.
  3. 2Refers to using fertility treatments to achieving the pregnancy such as fertility enhancing drugs, artificial insemination and artificial reproductive techniques (in vitro fertilization, intracytoplasmic sperm injection, fresh and donor embrio transfer etc.).
  4. 3Other interventions including prostaglandins for induction of labour as classified by Canadian Classification of Health Interventions under section 5, antepartum interventions.
  5. *Comparison between normal weight and overweight women.
  6. †Comparison between normal weight and obese women.
  7. Omnibus test p-values were found significant for type of labour onset (p < 0.001), mode of delivery (p < 0.001), and epidural analgesia (p < 0.001) and not significant for any other variables included in the table.
  8. Percentages are calculated per column for each variable.
  9. BMI, body mass index.
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BMC Pregnancy and Childbirth

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