Table 2

Relative risks of late and moderately preterm (LMPT) birth for lifestyle factors from multivariable model, before and after including mother's age, ethnicity, body mass index (BMI) and educational level

IndicatorRisk of late and moderate preterm birth
Model including lifestyle factorsModel including lifestyle factors adjusted for socio-demographic factors
Relative risk95% CIp ValueRelative risk95% CIp Value
Lifestyle factors
Use of recreational drugs during pregnancy
 Yes1.270.65 to 2.511.270.64 to 2.50
Smoking status
 Gave up before pregnancy0.860.67 to 1.090.930.72 to 1.20
 Gave up in first trimester1.070.73 to 1.561.120.76 to 1.66
 Smoker during pregnancy1.351.05 to 1.721.381.04 to 1.84
Alcohol use
 Gave up before pregnancy0.830.66 to to 1.34
 Gave up in first trimester0.780.61 to 0.990.980.73 to 1.31
 Drank during pregnancy0.860.66 to to 1.48
Daily consumption of five fruit and vegetables
 At least once a week10.02210.027
 Never1.311.04 to 1.641.311.03 to 1.66
Mediterranean diet factors
 None1.711.00 to 2.921.811.04 to 3.14
Socio-demographic factors
Mother's age (years)
 20–291.310.86 to 1.99
 30–391.370.88 to 2.13
 40+1.320.71 to 2.45
Mother's educational level
 Degree level and above10.052
 University-access level1.291.00 to 1.66
 Upper secondary qualification1.361.06 to 1.76
 No formal/lower secondary qualification1.421.06 to 1.89
Mother's ethnicity
 Mixed1.700.97 to 2.99
 Asian or Asian British1.541.13 to 2.11
 Black or Black British1.360.89 to 2.08
 Chinese or other ethnic group1.990.87 to 4.55
Mother's BMI
 <201.120.75 to 1.67
 25.0–29.90.800.64 to 1.00
 ≥300.580.45 to 0.76
 No pre-pregnancy weight recorded1.070.57 to 2.02