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Table 1 Characteristics of the study participants (n = 797,056)

From: Preterm birth and future risk of maternal cardiovascular disease – is the association independent of smoking during pregnancy?

  Women with term birth (n = 737,493) n (%) Women with preterm birth (n = 59,563) n (%)
Age group   
<20 19,146 (2.6) 1,635 (2.7)
20-34 524,443 (71.1) 40,334 (67.8)
≥35 193,904 (26.3) 17,594 (29.5)
Country of birth   
Other 56,046 (7.6) 4,348 (7.3)
Asia 110,122 (14.9) 7,526 (12.6)
Australia/NZ 515,753 (69.9) 44,122 (74.1)
Europe/North America 55,572 (7.6) 3,567 (6.0)
SEIFA index   
1st quintile (most advantaged) 145,600 (19.7) 9,761 (16.4)
2nd quintile 137,434 (18.6) 10,205 (17.2)
3rd quintile 152,245 (20.6) 12,831 (21.5)
4th quintile 147,983 (20.2) 12,475 (20.9)
5th quintile (most disadvantaged) 154,231(20.9) 14,291 (24.0)
Number of births   
1 220,409 (29.9) 13,284 (22.3)
2 291,368 (39.5) 21,461 (36.0)
≥3 225,716 (30.6) 24,818 (41.7)
Smoking during pregnancy   
Never 602,684 (81.7) 41,683 (70.0)
Smoking before last pregnancy 26,914 (3.7) 4,308 (7.2)
Smoking during last pregnancy 107,895 (14.6) 13,572 (22.8)
Gestational diabetes   
Never 690,275 (93.6) 54,163 (90.9)
Ever 47,218 (6.4) 5,400 (9.1)
Diabetes   
No 734,281 (99.6) 58,768 (98.7)
Yes 3,212 (0.4) 795 (1.3)
Having a fetal death   
Never 734,399 (99.6) 53,539 (89.9)
Ever 3,094 (0.4) 6,024 (10.1)
Having an SGA infant   
Never 631,749 (85.7) 48,769 (81.9)
3- <10th percentiles 75,580 (10.2) 7,131 (12.0)
<3rd percentiles 30,164 (4.1) 3,663 (6.1)