Table 3.

Unadjusted and adjusted odds ratios (OR) for caesarean section by onset of labour and maternal and infant characteristics

Characteristics	Total number	CAESAREAN SECTION
		N	Unadjusted OR (95 % CI)	Adjusted1 OR (95 % CI)
Labour onset
Spontaneous	242	30	reference	reference
Induction	220	47	1.9 (1.1-3.2)	1.9 (1.1-3.5)
Parity
≥1	265	13	reference	reference
0	197	64	9.3 (4.9-17.5)	14 (6.8-29)
Age (years)
<35	343	56	reference	reference
≥35	119	21	1.1 (0.6-1.9)	1.9 (1.1-3.7)
Gestational length (weeks)
<36	91	15	1.2 (0.6-2.4)	1.2 (0.5-3.1)
36-38	279	24	reference	reference
>38	92	38	2.2 (1.2-3.9)	1.8 (0.9-3.9)
Complication to the pregnancy
No	316	46	reference	reference
Yes	146	28	1.6 (0.9-2.6)	1.1 (0.6-1.8)
Birth weight 1st twin (g)
<2474	115	21	1.3 (0.7-2.3)	1.1 (0.5-2.3)
2474-3050	235	35	reference	reference
>3050	112	21	1.3 (0.7–2.4)	1.7 (0.8-3.6)
Birth weight 2nd twin (g)
<2449	115	21	1.2 (0.7-2.3)	1.1 (0.5-2.6)
2449-3075	233	34	reference	reference
>3075	114	23	1.5 (0.8-2.6)	1.6 (0.8-3.4)

¹Adjusted for maternal age, gestational length, parity, complications to the pregnancy, weight of first twin (percentiles) and year of birth