Table 2 Distribution of absolute frequency and association of socio-demographic, perinatal and neonatal characteristics on Infant Mortality in Porto Alegre (Rio Grande do Sul, Brazil) from 2000 to 2017

 10 to 17 years

24,882 (7.8)

370 (1.5)

1.59[1.42–1.77]

< 0.001

  ≥ 35 years

52,952 (16.7)

493 (0.9)

0.99 [0.90–1.09]

0.926

 18 to 34 years

239,706 (75.5)

2242 (0.9)

1

 Single/Separated/Widowed

203,417 (64.2)

2317 (1.1)

1.69 [1.56–1.83]

< 0.001

 Married/stable union

113,361 (35.8)

764 (0.7)

1

 Primipara

142,143 (44.8)

1180 (0.8)

0.76 [0.71–0.82]

< 0.001

 Multipara

174,796 (55.2)

1907 (1.1)

1

  ≥ 1

30,460 (9.6)

377 (1.2)

1.30 [1.17–1.45]

< 0.001

 None

287,004 (90.4)

2727 (1.0)

1

 None

9713 (3.1)

457 (4.7)

9.45 [8.48–10.53]

< 0.001

 From 1 to 3

25,711 (8.1)

668 (2.6)

5.22 [4.74–5.74]

< 0.001

 From 4 to 6

65,898 (20.8)

874 (1.3)

2.66 [2.44–2.91]

< 0.001

 7 and more

215,170 (68.0)

1071 (0.5)

1

 Vaginal

170,220 (53.6)

1671 (1.0)

1.0 [0.94–1.08]

0.828

 Cesarean

147,320 (46.4)

1435 (1.0)

1

 Less than 27 weeks

1317 (0.4)

749 (56.9)

124.96 [116.31–134.25]

< 0.001

 28 to 31 weeks

2631 (0.8)

397 (15.1)

33.15 [29.83–36.85]

< 0.001

 32 to 36 weeks

26,244 (8.3)

587 (2.2)

4.91 [4.46–5.41]

< 0.001

 37 weeks or more

286,735 (90.5)

1305 (0.5)

1

  < 7

3587 (1.1)

940 (26.2)

41.19 [38.39–44.19]

< 0.001

  ≥ 7

312,140 (98.9)

1986 (0.6)

1

 No (≥2500 g)

290,659 (91.5)

1294 (0.4)

0.07 [0.06–0.07]

< 0.001

 Yes (< 2500 g)

26,886 (8.5)

1813 (6.7)

1

 Yes

4711 (1.5)

791 (16.8)

23.02 [21.34–24.83]

< 0.001

 No

311,361 (98.5)

2271 (0.7)

1

 Female

154,886 (48.8)

1411 (0.9)

0.88 [0.82–0.95]

< 0.001

 Male

162,630 (51.2)

1680 (1.0)

1

 Public

147,558 (46.6)

1774 (1.2)

3.50 [3.09–3.97]

< 0.001

 Mixed

85,357 (27.0)

945 (1.1)

3.23 [2.83–3.69]

< 0.001

 Private

83,456 (26.4)

286 (0.3)

1