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Table 1 Socio-demographic determinants of smoking during pregnancy: percentage of smoking and adjusted odds ratios (AOR) from multiple logistic regression analysis

From: Socio-demographic factors associated with smoking and smoking cessation among 426,344 pregnant women in New South Wales, Australia

Socio-demographic characteristics Total number of women (%) % of smokers (n = 72,428) ΨAdjusted odds ratio (95% CI)
Year of delivery#    
1999–2003 426344 (100.0) 17.0  
1999 85655 (20.2) 19.0 1.00
2000 86439 (20.3) 17.4 0.91 (0.88–0.93)*
2001 84362 (19.8) 17.1 0.87 (0.85–0.89)*
2002 84573 (19.8) 16.4 0.83 (0.81–0.85)*
2003 85015 (19.9) 15.1 0.77 (0.75–0.79)*
Maternal age (years)#    
Under 20 years 18778 (4.4) 42.9 3.73 (3.58–3.89)*
20–34 329834(77.4) 16.9 1.31 (1.27–1.34)*
35+ 77553(18.2) 11.2 1.00
Aboriginal status#    
Non Aboriginal 415583(97.5) 16.0 1.00
Aboriginal 10579 (2.5) 57.8 3.43 (3.29–3.58)*
Parity#    
Primiparous 177304 (41.6) 14.3 1.00
Multiparous 248991 (58.4) 18.9 1.49 (1.46–1.51)*
Country of birth#    
Australian born 309580 (72.7) 20.5 1.00
NZ and Oceania 17809(4.2) 18.9 0.75 (0.72–0.78)*
UK & Ireland 12866 (3.0) 11.6 0.77 (0.73–0.82)*
Other Europe 11195 (2.6) 10.1 0.51 (0.47–0.54)*
Middle East 16864 (4.0) 8.3 0.25 (0.24–0.27)*
Asia 46721 (11.0) 1.8 0.066 (0.06–0.07)*
America/Africa 7313 (1.7) 5.2 0.24 (0.22–0.26)*
Others 3680 (0.9) 7.0 0.44 (0.39–0.50)*
Socio-economic status (SES)#    
Lowest SES 166987 (39.5) 22.3 3.33 (3.23–3.43)*
Moderate SES 168661 (39.9) 16.9 2.40 (2.32–2.47)*
Highest SES 87404 (20.7) 6.6 1.00
Booking in#    
Booked 416223 (97.6) 16.5 1.00
Unbooked 10120(2.4) 36.7 1.52 (1.44–1.61)*
Weeks at 1st antenatal visit#    
0–12 weeks 245729 (58.2) 14.4 1.00
13–26 weeks 156396 (37.0) 18.6 1.45 (1.42–1.47)*
27 weeks + 20314(4.8) 31.8 2.68 (2.58–2.77)*
  1. #Statistically significant (p < 0.05) in bivariate analyses; * ORs significant at p < 0.05 level; ΨThe fitted multiple logistic regression model is significant at p < 0.0001 (Model Chi square = 44067.74, df = 20), The model predicted overall 83.7% correctly classified (considering cut point 0.50). Dependent variable: Current smoking status (smoked yes = 1, no smoking = 0), Explanatory variables :Year of delivery, maternal age, Aboriginal status, parity, country of birth, SES, booking in and weeks of gestation at first antenatal care. For all variables not stated and missing cases excluded from the analyses.