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. 2014 Sep 8;14:314. doi: 10.1186/1471-2393-14-314

Table 1.

Baseline characteristics of the cohort and comparisons with all births in the study region (with gestational 28 weeks or more)

Characteristics Frequency (percentage a)
Birth cohort sample (Years 2007 to 2010) 2254 women 2277 babies Deliveries in region b (Years 2007 to 2010) 36620 women 37061 babies p-value c (two-sided)
Maternal age
  < 20 years 107 (4.8%) 2559 (7.0%) < 0.001
  20-24 years 438 (19.9%) 6407 (17.6%)
  25-29 years 632 (28.6%) 10376 (28.5%)
  30-34 years 560 (25.4%) 10088 (27.7%)
  ≥ 35 years 469 (21.3%) 6980 (19.2%)
  Missing data 48 0
Gender of infant
  Male 1127 (50.3%) 18914 (51.3%) 0.324
  Female 1115 (49.7%) 17926 (48.7%)
  Missing data 35 0
Birthweight
  < 2500 g 55 (2.5%) 1800 (4.9%) < 0.001
  2500-3999 g 1809 (81.5%) 30207 (82.0%)
  ≥ 4000 g 355 (16.0%) 4831 (13.1%)
  Missing data 58 2
Gestational age at birth
 28-36 weeks 79 (3.5%) 2376 (6.4%) < 0.001
  37-41 weeks 2131 (95.9%) 34264 (93.0%)
  42 weeks 13 (0.6%) 200 (0.5%)
  Missing data 54 0
Plurality
  Singleton 2207 (98.0%) 35980 (97.7%)
  Multiple 46 (2.0%) 860 (2.3%) 0.370
  Missing data 24 0
Outcome
  Live birth 2273 (99.8%) 36728 (99.7%)
  Stillbirth 4 (0.2%) 112 (0.3%) 0.274
  Missing data 0 0

aPercentages are calculated based on the available (non-missing) data.

bData include only deliveries with gestational 28 weeks or more; data are provided by Queensland Health and New South Wales Health for the study region (Logan, Beaudesert, Gold Coast and Tweed).

cChi-square test for comparing proportions between birth cohort sample and the general population.