Skip to main content

Table 2 Analysis of survival

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 1. - 2. relative risk No. (%) p-value 96 - 00 No. (%) p-value 00 - 04 No. (%) p-value 04 - 08 No. (%) p-value 96 - 08
Overall mortality rate 412 (13.3)    95 (13.2) 0.04 122 (15.8) 0.04 98 (13.0) 0.20 97 (11.5) 0.15
Mortality rate by gender            
   1. females 177 (11.7) 0.55 1 41 (12.0) 0.26 54 (13.8) 0.07 38 (10.5) 0.91 44 (10.7) 0.41
   2. males 235 (14.8)   1.13 54 (14.3) 0.06 68 (17.7) 0.22 60 (15.3) 0.09 53 (12.3) 0.24
Mortality rate by mode of delivery1            
   1. spontaneous 107 (18.9) 0.17 1.65 33 (19.0) 0.70 29 (20.3) 0.54 23 (18.1) 0.95 22 (17.9) 0.75
   2. caesarean section 273 (11.4)   1 58 (11.1) < 0.01 86 (14.5) 0.03 70 (11.5) 0.03 59 (8.8) 0.06
Mortality rate by location of birth            
   1. inborn2 376 (13.4) 0.89 1.06 81 (13.0) 0.01 112 (16.3) 0.02 92 (12.9) 0.26 91 (11.6) 0.23
   2. outborn 36 (12.7)   1 14 (14.3) 0.43 10 (11.4) 0.60 6 (14.0) 0.51 6 (10.9) 0.47
Mortality rate by number of infants            
   1. singleton 308 (14.4) 0.50 1.31 75 (13.9) 0.17 87 (15.9) 0.30 73 (14.2) 0.60 73 (13.4) 0.75
   2. multiples 104 (11.0)   1 20 (11.2) 0.05 35 (15.4) 0.03 25 (10.4) 0.18 24 (8.1) 0.09
Mortality rate by gestational age3            
   < 26 186 (56.0)   6.8a 40 (58.8) 0.26 60 (64.5) 0.05 45 (54.2) 0.15 41 (46.6) 0.02
   26-27 115 (23.1)   4.7a 25 (26.0) 0.95 34 (25.8) 0.51 30 (23.3) 0.17 26 (18.4) 0.04
   28-29 52 (7.5)   2.0a 14 (8.2) 0.69 13 (7.4) 0.83 12 (7.0) 0.92 13 (7.3) 0.50
   30-31 46 (4.0)   1.3a 11 (4.0) 0.78 10 (3.7) 0.68 9 (3.2) 0.77 16 (5.0) 0.32
Characteristics p0.5 (p0.05-p0.95) p-value 1. - 2. mean p-value 96 - 00 Mean p-value 00 - 04 mean p-value 04 - 08 mean p-value 96 - 08
Birth weight (g)            
   1. survivors 1225 (630-1840) < 0.001 1283 0.49 1279 0.94 1264 0.05 1244 0.01
   2. deaths 795 (480-1625)    943 0.02 835 0.11 918 0.79 935 0.89
Gestational age (week)            
   1. survivors 30 0/7 (25 0/7 - 33 5/7) < 0.001 30 2/7 0.56 30 0/7 0.96 29 6/7 0.02 29 6/7 < 0.01
   2. deaths 26 3/7 (23 6/7 - 31 5/7)    27 2/7 0.10 26 5/7 0.90 26 5/7 0.32 27 0/7 0.52
  1. p0.5 = 50th percentile = median, p0.05 = 5th percentile, p0.95 = 95th percentile, 1cephalic forceps and cephalic ventouse deliveries were not listed separately, 2 inborn = born in one oft the nine perinatal centres, 3 children born > 32 completed gestational weeks were not listed separately, a relative to the older age groups