Skip to main content

Table 2 Baseline characteristics according to class of maternal age (years) among multiple preterm births. Lombardy, Italy, 2007–2017

From: The role of maternal age on the risk of preterm birth among singletons and multiples: a retrospective cohort study in Lombardy, Northern Italy

 

Maternal age group

< 20 (N = 42)

20–24 (N = 254)

25–29 (N = 1105)

30–34 (N = 2668)

35–39 (N = 2972)

≥40 (N = 911)

p-value

Year of birth

 2007

3 (7.1)

19 (7.5)

96 (8.7)

229 (8.6)

197 (6.6)

26 (2.9)

< 0.0001

 2008

3 (7.1)

22 (8.7)

106 (9.6)

272 (10.2)

235 (7.9)

32 (3.5)

 

 2009

4 (9.5)

19 (7.5)

89 (8.1)

276 (10.3)

279 (9.4)

66 (7.24)

 

 2010

3 (7.1)

17 (6.7)

92 (8.3)

242 (9.1)

271 (9.1)

72 (7.9)

 

 2011

6 (14.3)

22 (8.7)

126 (11.4)

249 (9.3)

297 (10.0)

77 (8.45)

 

 2012

1 (2.4)

32 (12.6)

108 (9.8)

230 (8.6)

270 (9.1)

97 (8.5)

 

 2013

6 (14.3)

20 (7.9)

121 (11.0)

270 (10.1)

298 (10.0)

95 (10.4)

 

 2014

5 (11.9)

31 (12.2)

99 (9.0)

257 (9.6)

297 (10.0)

131 (14.4)

 

 2015

7 (16.7)

23 (9.1)

80 (7.2)

202 (7.6)

288 (9.7)

114 (12.5)

 

 2016

2 (4.8)

28 (11.0)

99 (9.0)

220 (8.3)

278 (9.4)

109 (12.0)

 

 2017

2 (4.8)

21 (8.3)

89 (8.1)

221 (8.3)

262 (8.8)

92 (10.1)

 

Maternal citizenship

 Italian

28 (66.7)

171 (67.3)

862 (78.0)

2265 (84.9)

2610 (87.8)

820 (90.0)

< 0.0001

 Not Italian

14 (33.3)

83 (32.7)

243 (22.0)

403 (15.1)

362 (12.2)

91 (10.0)

 

Marital status a

 Married

7 (17.1)

110 (44.00)

712 (66.1)

1991 (76.8)

2134 (73.3)

560 (63.0)

< 0.0001

 Not married

34 (82.9)

140 (56.00)

366 (33.9)

600 (23.2)

776 (26.7)

329 (37.0)

 

Maternal education b

 Middle school

32 (78.1)

123 (48.4)

368 (33.4)

528 (19.9)

545 (18.4)

145 (15.9)

< 0.0001

 High school

8 (19.5)

116 (45.7)

531 (48.2)

1218 (45.8)

1237 (41.7)

387 (42.5)

 

 University

1 (2.5)

15 (5.9)

202 (18.4)

912 (34.3)

1183 (39.9)

378 (41.5)

 

Maternal employment

 Employed

4 (9.5)

102 (40.2)

790 (71.5)

2143 (80.3)

2470 (83.1)

782 (85.8)

< 0.0001

 Not employed

38 (90.5)

152 (59.8)

315 (28.5)

525 (19.7)

502 (16.9)

129 (14.2)

 

Mode of conception

 Spontaneous

42 (100.0)

246 (96.9)

963 (87.2)

2061 (77.3)

1958 (65.9)

333 (36.6)

< 0.0001

 Non spontaneous

0 (0.0)

8 (3.1)

142 (12.8)

607 (2.7)

1014 (34.1)

578 (63.5)

 

Diabetes

 No

42 (100.0)

253 (99.6)

1099 (99.5)

2637 (98.8)

2938 (98.9)

899 (98.7)

0.3693

 Yes

0 (0.0)

1 (0.4)

6 (0.5)

31 (1.2)

34 (1.1)

12 (1.3)

 

Hypertension

 No

38 (90.5)

250 (98.4)

1072 (97.0)

2601 (97.5)

2893 (97.3)

870 (95.5)

0.0022

 Yes

4 (9.5)

4 (1.6)

33 (3.0)

67 (2.5)

79 (2.7)

41 (4.5)

 
  1. aNot included 193 missing data
  2. b Not included 23 missing data