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Table 1 Maternal characteristics and pregnancy outcomes among women delivering between 1973 and 2012 in Sweden, stratified by exposure to preterm delivery before 37 weeks (n = 1,943,716)

From: Risk of long-term renal disease in women with a history of preterm delivery: a population-based cohort study

 No preterm delivery, n (%)
N = 1,780,798 (91.6)
Preterm delivery, n (%)
N = 162,918 (8.4)
Age in years
 < 2097,007 (5.5)14,384 (8.8)
 20–291,151,931 (64.7)104,337 (64.0)
 30–39507,226 (28.5)41,921 (25.7)
 ≥ 4024,634 (1.4)2276 (1.4)
Native country
 Sweden1,509,135 (84.7)138,441 (85.0)
 Elsewhere271,663 (15.3)24,477 (15.0)
Education level
 Less than upper secondary233,341 (13.1)24,540 (15.1)
 Upper secondary800,419 (45.0)77,826 (47.8)
 Third level709,299 (39.8)57,702 (35.4)
 Missing37,739 (2.1)2850 (1.8)
Body mass index in early pregnancy (kg/m2)
 Underweight, < 18.541,129 (2.3)4830 (3.0)
 Normal, 18.5–24.9655,619 (36.8)55,415 (34.0)
 Overweight, 25–29.9178,593 (10.0)15,447 (9.5)
 Obese, ≥ 3064,011 (3.6)6445 (4.0)
 Missing841,446 (47.3)80,781 (49.6)
Maternal smoking
 No950,672 (53.4)83,138 (51.0)
 Yes187,197 (10.5)21,404 (13.1)
 Missing642,929 (36.1)58,376 (35.8)
Gestational diabetes (ever)
 No1,764,968 (99.1)160,133 (98.3)
 Yes15,830 (0.9)2785 (1.7)
Preeclampsia (ever)
 No1,709,392 (96.0)141,702 (87.0)
 Yes71,406 (4.0)21,216 (13.0)
Small for gestational age (SGA) (ever)
 No1,700,028 (95.6)140,572 (86.5)
 Yes77,671 (4.4)22,008 (13.5)
Decade of first birth
 1973–1979478,412 (26.9)39,063 (24.0)
 1980–1989385,271 (21.6)42,506 (26.1)
 1990–1999386,441 (21.7)38,576 (23.7)
 2000–2012530,674 (29.8)42,773 (26.3)
Parity
 1610,494 (34.3)38,564 (23.7)
 2793,672 (44.6)70,936 (43.5)
 3291,217 (16.4)35,819 (22.0)
 464,811 (3.6)11,970 (7.4)
 5 or more20,604 (1.2)5629 (3.5)