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Table 1 Demographic changes of the study population from 1996 to 2008

From: Population based trends in mortality, morbidity and treatment for very preterm- and very low birth weight infants over 12 years

Year 1996-2008 1996   2000   2004   2008  
Characteristics No. (%)   p-value 1996-2000 No. (%) p-value 2000-2004 No. (%) p-value 2004-2008 No. (%) p-value 1996-2008
Very preterm infants1 2665 (86.2) 606 (84.2) 0.07 674 (87.1) 0.24 662 (87.8) 0.04 723 (85.9) 0.23
Very low birth weight infants2 425 (13.8) 114 (15.8) 0.03 100 (12.9) 0.57 92 (12.2) 0.09 119 (14.1) 0.18
Small for gestational age3 576 (18.6) 146 (20.3) 0.06 136 (17.6) 0.90 134 (17.8) 0.36 460 (19.0) 0.35
Gender          
   - female 1507 (48.8) 342 (47.5) 0.11 390 (50.4) 0.22 363 (48.1) 0.65 412 (48.9) 0.41
   - male 1583 (51.2) 378 (52.5)   384 (49.6)   391 (51.9)   430 (51.1)  
Location of birth          
   - inborn4 2806 (90.8) 622 (86.4) 0.07 686 (88.6) < 0.001 711 (94.3) 0.30 787 (93.5) < 0.001
   - outborn 284 (9.2) 98 (13.6)   88 (11.4)   43 (5.7)   55 (6.5)  
Mode of delivery5          
   - spontaneous 567 (18.3) 174 (24.2) < 0.001 143 (18.5) 0.24 127 (16.8) 0.09 123 (14.6) < 0.001
   - caesarean section 2395 (77.5) 521 (72.4) < 0.01 595 (76.9) < 0.01 610 (80.9) 0.29 669 (79.5) < 0.001
Number of infants          
   - singleton 2144 (69.4) 541 (75.1) < 0.01 546 (70.5) 0.13 513 (68.0) 0.03 544 (64.6) < 0.001
   - multiples 946 (30.6) 179 (24.9)   228 (29.5)   241 (32.0)   298 (35.4)  
Characteristics p0.5 (p0.05-p0.95) Mean p-value 1996-2000 Mean p-value 2000-2004 Mean p-value 2004-2008 Mean p-value 1996-2008
Gestational age (week) 30 0/7 (25 0/7 - 33 5/7) 29 6/7 < 0.01 29 3/7 1 29 3/7 0.35 29 4/7 0.04
Birth weight (g) 1225 (630 - 1840) 1238 0.13 1209 0.56 1220 0.51 1208 0.11
  1. p0.5 = 50th percentile = median, p0.05 = 5th percentile, p0.95 = 95th percentile, 1 infants born < 32 weeks of gestation, 2 infants born ≥32 weeks of gestation with a birth weight < 1500 g, 3 birth weight < 10th percentile, 4 born in one of the nine perinatal centres, 5 cephalic forceps and cephalic ventouse deliveries were not listed separately