Table 4

Differences in maternal characteristics between disclosures and non-disclosures of smoking status

P values
BCO level (ppm) (median, IQR)10.0 (8.0)4.0 (3.0)<0.01
Age (years) (mean, SD)27.3 (5.0)29.7 (5.2)NS
BMI (kg/m2) (mean, SD)26.5 (8.4)27.7 (7.1)NS
Married (%)15.832.0NS
Nulliparas (%)34.252.0NS
Planned pregnancy (%)36.860.0<0.05
Age completed education (years) (mean, SD)*17.9 (2.1)20.9 (3.9)<0.05
Continuous years of education (mean, SD)*13.4 (2.4)16.5 (3.6)<0.01
Weekly alcohol before pregnancy (%)57.972.0NS
Alcohol binge before pregnancy (%)23.752.0<0.01
Drug use before pregnancy (%)26.320.0NS
Weekly alcohol in pregnancy (%)2.64.0
Alcohol binge in pregnancy (%)2.60.0
Drug use in pregnancy (%)10.512.0
Smoked in previous pregnancy (%)55.320.0<0.01
Exposed to passive smoked daily (%)73.756.0NS
Exposure to passive smoke (hours) (mean, SD)3.9 (3.5)1.5 (1.6)<0.05
  • P values in final column indicate differences between disclosures and non-disclosures.

  • *Missing data n=67.

  • -   The number of values for this variable was too small to statistically analyse 

  • BCO, breath carbon monoxide; BMI, Body Mass Index; NS, not significant.