Table 5 The risk of caesarean sections (CS) in relation to age of the mother (years), parity, litter size at birth and (LSB)

Bitch age (years)

Age 1–2

28.9 (242)

Reference

Reference

Age 3

35.4 (237)

1.79 (1.14–2.81)

0.011

Age 4

33.9 (168)

2.22 (1.27–3.88)

0.0050

Age 5

35.0 (100)

3.25 (1.58–6.71)

0.0014

Age ≥ 6

33.3 (51)

4.82 (1.80–12.86)

0.0017

Parity

Parity 1

36.2 (426)

Reference

Reference

Parity 2

31.4 (236)

0.49 (0.31–0.77)

0.0019

Parity 3

27.6 (98)

0.30 (0.15–0.59)

 < 0.001

Parity ≥ 4

21.1 (38)

0.15 (0.05–0.46)

 < 0.0011

LSB

LSB 1–2

50.5 (107)

Reference

Reference

LSB 3–4

35.6 (163)

0.49 (0.28–0.85)

0.011

LSB 5–7

26.8 (257)

0.36 (0.21–0.60)

 < 0.001

LSB 8–9

26.7 (172)

0.35 (.020–0.61)

 < 0.001

LSB ≥ 10

36.4 (99)

0.57 (0.31–1.06)

0.077

Season^a

Winter

32.2 (174)

Reference

0.90

Spring

32.6 (291)

1.04 (0.67–1.62)

–

Summer

32.6 (178)

0.97 (0.59–1.59)

–

Autumn

34.8 (155)

1.17 (0.70–1.93)

–

Stillbirth in the litter

Stillbirth

31.6 (412)

0.97 (0.70–1.36)

0.88