Table 1

Description of the study population

	Total births		Preterm births		p Value	Early-term births		p Value
	N	Percent	N	Percent	p Value	N	Percent	p Value
Total	446 492		24 482	5.48		120 995	27.10
Gender
Male	229 847	51.48	13 611	5.92	<0.001	63 181	27.49	<0.001
Female	216 645	48.52	10 871	5.02		57 814	26.69
Maternal age (years)
<25	50 683	11.35	2699	5.33	<0.001	11 751	23.19	<0.001
25–35	282 078	63.18	14 812	5.25		73 871	26.19
>35	113 731	25.47	6971	6.13		35 373	31.10
Parity
Primiparous	222 317	49.79	14 281	6.42	<0.001	54 430	24.48	<0.001
Multiparous	224 175	50.21	10 201	4.55		66 565	29.69
Civil status*
Single	70 938	15.89	4576	6.45	<0.001	17 167	24.20	<0.001
Married	363 297	81.37	18 988	5.23		99 975	27.52
Others	12 257	2.75	918	7.49		3853	31.44
Nationality
Non-Swiss	166 787	37.35	8915	5.35	0.002	45 335	27.18	0.339
Swiss	279 705	62.65	15 567	5.57		75 660	27.05

Preterm birth (22–36 gestational weeks); early-term birth (37–38 gestational weeks).
*Civil status: ‘other’ refers to other single status (widow, divorced, partner, etc).
p Value: χ².
N, total number of cases.