Table 3 Risk factors for cesarean delivery among nulliparous women with singleton, cephalic, term pregnancies^a

Age at delivery (year)

 < 25

80 (27)

Reference

Reference

 25–29

107 (46)

2.3 (1.6–3.4)

 < 0.01

2.3 (1.5–3.4)

 < 0.01

 30–34

91 (56)

3.5 (2.3–5.2)

 < 0.01

3.3 (2.1–5.1)

 < 0.01

 ≥ 35

87 (69)

6.2 (3.9–9.8)

 < 0.01

5.6 (3.4–9.2)

 < 0.01

Pre-pregnancy body mass index^b

 Underweight

46 (31)

0.6 (0.4–0.9)

 < 0.01

0.7 (0.5–1.1)

0.14

 Normal

221 (44)

Reference

Reference

 Overweight

52 (53)

1.5 (0.9–2.2)

0.09

1.2 (0.7–2.0)

0.42

 Obese

38 (73)

3.5 (1.9–6.6)

 < 0.01

2.5 (1.2–5.1)

0.01

 Unknown

8 (73)

3.4 (0.9–13.1)

0.07

2.7 (0.6–12.1)

0.20

Existing blood condition^c

 No

363 (46)

Reference

Reference

 Yes

2 (8)

0.1 (0.02–0.5)

 < 0.01

0.08 (0.01–0.5)

0.01

New medical condition during the current pregnancy^{b, d}

 No

354 (44)

Reference

Reference

 Yes

11 (92)

14.0 (1.8–108.6)

0.01

35.1 (2.3–527.0)

0.01

Fetal distress during current delivery^b

 No

331 (43)

Reference

Reference

 Yes

34 (89)

11.5 (4.0–32.6)

 < 0.01

16.1 (5.4–47.6)

 < 0.01

Dysfunctional labor/failure to progress during current delivery^b

 No

349 (44)

Reference

Reference

 Yes

16 (84)

6.8 (2.0–23.6)

 < 0.01

6.3 (1.7–24.2)

 < 0.01

Baby size for gestational age percentile based on INTERGROWTH-21st standard^b

 < 10^th

28 (29)

Reference

Reference

 10-19^th

35 (31)

1.1 (0.6–2.0)

0.74

1.2 (0.6–2.3)

0.65

 20-29^th

32 (36)

1.4 (0.7–2.6)

0.31

1.2 (0.6–2.5)

0.55

 30-39^th

35 (41)

1.7 (0.9–3.2)

0.09

1.5 (0.8–3.0)

0.24

 40-49^th

32 (39)

1.6 (0.9–3.0)

0.14

1.6 (0.8–3.2)

0.18

 50-59^th

40 (51)

2.6 (1.4–4.3)

 < 0.01

2.3 (1.1–4.5)

0.02

 60-69^th

41 (48)

2.3 (1.3–4.3)

0.01

2.1 (1.1–4.1)

0.03

 70-79th

41 (59)

3.7 (1.9–7.0)

 < 0.01

2.8 (1.3–5.7)

 < 0.01

 80-89^th

43 (69)

5.7 (2.8–11.3)

 < 0.01

5.5 (2.6–11.8)

 < 0.01

 ≥ 90^th

37 (79)

9.2 (4.0–21.1)

 < 0.01

6.9 (2.3–16.8)

 < 0.01

 Unknown

1 (25)

0.8 (0.1–8.6)

0.88

0.8 (0.1–8.2)

0.84

Self-pay for delivery fees

 Yes

65 (54)

1.5 (1.0–2.3)

0.03

1.7 (1.1–2.8)

0.02

 No

300 (43)

Reference

Reference