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Table 2 Demographic and socioeconomic parameters in singleton pregnancies.

From: Analysis of preterm deliveries below 35 weeks' gestation in a tertiary referral hospital in the UK. A case-control survey

  Control (≥ 37 weeks' gestation) Preterm (<35 weeks' gestation) P value
Number of deliveries 553 228  
Median gestational age at delivery (completed weeks) and range 40 (Range 37-42) 33 (Range 23 - 34) Not Applicable
Maternal age    
Mean maternal age at delivery (years) 28.8 (SD 6.04)
(Range 15-44)
29.4 (SD 6.69)
(Range16-46)
0.24
   ≤ 18 years 33 (6.0%) 13 (5.7%)  
   19-39 years 509 (92.0%) 199 (87.3) 0.002
   >39 years 11 (2.0%) 16 (7.0%) (Comparison of proportions of mothers >39 years P < 0.001)
Body mass index    
Mean BMI at booking (kg/m2) 25.03 (SD 5.29)
(Range 16-49)
(n = 531)
25.8 (SD 6.71)
(Range 15-60)
(n = 195)
0.10
   Lean <20 42 (7.9%) 24 (12.3%) 0.054
   Normal 20 - 29.9 402 (75.7%) 131 (67.2%)  
   Obese ≥30 87 (16.4%) 40 (20.5%)  
Socioeconomic    
With social problems 60/548 (10.9%) 50/218 (22.9%) <0.001
Smoking during pregnancy 114/553 (20.6%) 83/226 (36.7%) <0.001
Drinking Alcohol during pregnancy 180/550 (32.7%) 75/228 (32.9%) 0.96
Using drugs during pregnancy 20/553 (3.6%) 12/226 (5.3%) 0.28