Rate of spontaneous onset of labour before planned repeat caesarean section at term

Roberts, Christine L; Nicholl, Michael C; Algert, Charles S; Ford, Jane B; Morris, Jonathan M; Chen, Jian Sheng

doi:10.1186/1471-2393-14-125

Table 2 Among low risk women for elective repeat caesarean section (ERCS), the factors associated with spontaneous labour at 37-38 weeks

From: Rate of spontaneous onset of labour before planned repeat caesarean section at term

	Total low risk women N = 17,314	Spontaneous labour <39 weeks N = 1,473		Crude RR (95% CI)	Adjusted RR^b(95% CI)
		N	Rate (Row%)^a
Age (years)
<20	106	10	9.4	1.12 (0.62, 2.02)
20 - <35	10,927	922	8.4	1.00
> = 35	6,280	541	8.6	1.02 (0.92, 1.13)
Country of birth
Australian	12,663	1,013	8.0	1.00	1.00
Asian	2,238	258	11.5	1.44 (1.27, 1.64)	1.53 (1.33, 1.75)
Other	2,376	199	8.4	1.05 (0.91, 1.21)	1.09 (0.94, 1.26)
Socio-economic status
Most disadvantaged	3,144	293	9.3	1.00
Disadvantaged	3,017	254	8.4	0.90 (0.77, 1.06)
Average	2,997	263	8.8	0.94 (0.80, 1.10)
Advantaged	3,341	259	7.8	0.83 (0.71, 0.98)
Most advantaged	4,596	386	8.4	0.90 (0.78, 1.04)
Smoking in pregnancy	1,561	176	11.3	1.37 (1.18, 1.59)	1.33 (1.14, 1.56)
No. of previous vaginal births
0	14,972	1,256	8.4	1.00	1.00
1	1,394	133	9.5	1.14 (0.96, 1.35)	0.94 (0.80-1.12)
≥2	531	53	10.0	1.19 (0.92, 1.54)	0.89 (0.68-1.15)
No. of previous CS
1	12,562	1,013	8.1	1.00	1.00
2	3,673	358	9.8	1.21 (1.07, 1.35)	1.16 (1.04, 1.30)
≥3	703	73	10.4	1.28 (1.03, 1.61)	1.16 (0.92, 1.45)
Prior delivery history ^c
Spontaneous preterm	402	102	25.4	4.31 (3.57, 5.20)	4.12 (3.38, 5.03)
Planned preterm	447	65	14.5	2.49 (1.96, 3.16)	2.47 (1.94, 3.14)
Spontaneous term	5,255	570	10.8	1.85 (1.65, 2.08)	1.85 (1.65, 2.07)
Planned term	8,722	512	5.9	1.00	1.00
Unavailable	2,488	224	9.0	1.54 (1.32, 1.79)	1.39 (1.19, 1.63)
Vertex Presentation	16,911	1,440	8.5	1.04 (0.75, 1.45)
Size at birth
<10^th percentile	903	81	9.0	1.03 (0.83, 1.27)
10^th - 90^th percentile	13,674	1,194	8.7	1.00
>90^th percentile	2,729	197	7.2	0.83 (0.72, 0.96)
Care type (private)	8,324	700	8.4	0.98 (0.89, 1.08)
Antenatal care (<20w)	16,353	1,390	8.5	0.98 (0.80, 1.22)
Birth hospital type
Private	6,597	533	8.1	0.96 (0.85, 1.08)
Tertiary	5,743	483	8.4	1.00
Other (urban)	2,409	225	9.3	1.11 (0.96, 1.29)
Other (rural)	2,565	232	9.0	1.08 (0.93, 1.25)

^aUnadjusted rate of spontaneous labour <39 weeks for each characteristic.
^bAdjusted for other variables in the column.
^cIncorporates spontaneous onset of labour or planned delivery (by labour induction or prelabour caesarean section) for the lowest gestation of all prior births.

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