Table 1.

Incidence of early-term birth by maternal age, previous uterine scar, parity and precursors for delivery (n=73 567)

Characteristics	Total	Unweighted		Weighted
		Incidence (%)	95% CI	Incidence (%)	95% CI
Maternal age
<30	45 982	25.88	25.56 to 26.20	24.81	24.50 to 25.12
30–34	19 141	31.87	31.53 to 32.21	30.67	30.34 to 31.00
≥35	8444	35.14	34.80 to 35.48	34.38	34.04 to 34.72
Previous uterine scars
Yes	10 681	42.84	42.48 to 43.20	40.25	39.90 to 40.60
No	62 886	26.07	25.75 to 26.39	24.81	24.50 to 25.12
Parity
Nulliparous	41 302	24.96	24.65 to 25.27	23.27	22.96 to 23.58
Multiparous	32 265	33.04	32.70 to 33.38	30.84	30.51 to 31.17
Precursors for delivery
Spontaneous labour	33 958	24.82	24.51 to 25.13	23.94	23.63 to 24.25
PROM	8616	33.57	33.23 to 33.91	34.58	34.24 to 34.92
Indicated*	28 815	31.67	31.33 to 32.01	29.79	29.46 to 30.12
Elective induction or C-Section	2178	23.92	23.61 to 24.23	21.53	21.23 to 21.83

*‘Indicated’ precursors refer to women with maternal, fetal or obstetric complications.

C-Section, caesarean section; PROM, premature rupture of membranes.