Table 1

Demographic characteristics according to age group (years)

13–1516–1718–19All teenagers25–29p Value* for difference
N8412345987730551 142
Cohabitation status
 Married/cohabiting13 (15.5)598 (48.5)4248 (71.0)4859 (66.5)45 262 (88.5)<0.001
 Single45 (53.6)471 (38.2)1132 (18.9)1644 (22.5)2608 (5.1)
 Missing data26 (30.9)165 (13.3)607 (10.1)802 (11.0)3272 (6.4)
Type of residence
 Urban52 (61.9)820 (66.5)3980 (66.5)4852 (66.4)37 589 (73.5)<0.001
 Densely populated14 (16.7)185 (15.0)1050 (17.5)1249 (17.1)7313 (14.3)
 Rural16 (19.0)222 (18.0)930 (15.5)1168 (16.0)6035 (11.8)
 Missing data2 (2.4)7 (0.5)27 (0.5)36 (0.5)205 (0.4)
Smoking during pregnancy
 Yes28 (33.3)506 (41.3)2127 (35.5)2661 (36.4)3580 (7.0)<0.001
 Quit during first trimester11 (13.1)157 (12.7) 725 (12.1)893 (12.2)3324 (6.5)
 Missing data6 (7.1)37 (3.0)171 (2.9)214 (2.9)921 (1.8)
Alcohol or drug misuse during pregnancy3 (3.6)14 (1.1)65 (1.1)82 (1.1)96 (0.2)<0.001
BMI before pregnancy
 Underweight†16 (19.0)155 (12.6)57 (9.6)228 (10.3)1841 (3.6)<0.001
 Obese‡109 (1.3)63 (5.1)395 (6.6)567 (6.3)4347 (8.5)
 Missing data6 (7.1)57 (4.6)174 (2.9)237 (3.2)1074 (2.1)
History of spontaneous abortion(s)2 (2.4)51 (4.1)479 (8.0)532 (7.3)5984 (11.7)<0.001
Pre-existing hypertension0 (0)1 (0.1)6 (0.1)7 (0.1)102 (0.2)0.026
Pre-existing diabetes0 (0)7 (0.6)42 (0.7)49 (0.7)358 (0.7)0.834
  • Data expressed as n (%).

  • *p Values refer to differences between all the age groups.

  • †BMI <18.5 kg/m2.

  • ‡BMI≥30 kg/m2.

  • BMI, body mass index.