Table 4.

Mode of birth, intervention rates and perineal outcomes by planned place of birth

Intervention and planned place of birth	No. of events	No. of births	Incidence of events (%)	Unadjusted OR	Adjusted OR*
Normal vaginal birth	992 118	1 251 420	79.3
Hospital	920 514	1 171 703	78.6	1	1
Birth centre	63 790	71 505	89.2	2.26 (2.19–2.33)	2.72 (2.63–2.81)
Home	7814	8212	95.2	5.36 (4.69–6.12)	5.91 (5.15–6.78)
Vacuum extraction	88 586	1 251 420	7.1
Hospital	85 975	1 171 703	7.3	1	1
Birth centre	2503	71 505	3.5	0.44 (0.42–0.47)	0.42 (0.40–0.44)
Home	108	8212	1.3	0.19 (0.15–0.24)	0.18 (0.14–0.24)
Forceps birth	56 332	1 251 420	4.5
Hospital	54 451	1 171 703	4.6	1	1
Birth centre	1820	71 505	2.5	0.54 (0.50–0.57)	0.54 (0.50–0.58)
Home	61	8212	0.7	0.15 (0.11–0.21)	0.21 (0.14–0.31)
Intrapartum caesarean section	94 303	1 251 420	7.5
Hospital	91 238	1 171 703	7.8	1	1
Birth centre	2871	71 505	4	0.50 (0.47–0.52)	0.45 (0.43–0.48)
Home	194	8212	2.4	0.29 (0.24–0.35)	0.29 (0.24–0.35)
Mode of birth not stated	20 081	1 251 420	1.6
Hospital	19 525	1 171 703	1.7	1	1
Birth centre	521	71 505	0.7	0.43 (0.39–0.49)	0.41 (0.36–0.46)
Home	35	8212	0.4	0.25 (0.16–0.39)	0.26 (0.17–0.41)
Oxytocin augmentation	199 302	1 251 420	15.9
Hospital	193 229	1 171 703	16.5	1	1
Birth centre	5790	71 505	8.1	0.45 (0.43–0.46)	0.41 (0.40–0.43)
Home	283	8212	3.4	0.18 (0.15–0.21)	0.19 (0.16–0.22)
Epidural or spinal analgesia for labour	166 746	1 251 420	13.3
Hospital	161 796	1 171 703	13.8	1	1
Birth centre	4675	71 505	6.5	0.44 (0.42–0.45)	0.41 (0.39–0.43)
Home	275	8212	3.3	0.22 (0.18–0.25)	0.22 (0.19–0.26)
Intact perineum†	308 232	1 157 117	26.6
Hospital	283 887	1 080 465	26.3	1	1
Birth centre	20 562	68 634	30	1.20 (1.17–1.23)	1.39 (1.36–1.43)
Home	3783	8018	47.2	2.51 (2.37–2.66)	2.72 (2.56–2.90)
Episiotomy†	193 171	1 157 117	16.7
Hospital	187 276	1 080 465	17.3	1	1
Birth centre	5688	68 634	8.3	0.43 (0.42–0.45)	0.37 (0.36–0.39)
Home	207	8018	2.6	0.13 (0.11–0.15)	0.13 (0.10–0.15)
Third or fourth degree perineal trauma	23 165	1 157 117	2
Hospital†‡	21 454	1 080 465	2	1	1
Birth centre	1641	68 634	2.4	1.21 (1.13–1.29)	1.17 (1.09–1.25)
Home	70	8018	0.9	0.43 (0.32–0.59)	0.53 (0.36–0.73)

Cases with missing data were not included in rates or regression calculations.

Variables on mode of birth and intervention are as defined by each state or territory.

*Logistic regression adjusted for maternal age, country of birth, gestational age and parity at 99% CI.

†Denominator=excluded caesarean section.

‡Included episiotomy extensions.