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

Indicator	Risk of late and moderate preterm birth
	Model including lifestyle factors			Model including lifestyle factors adjusted for socio-demographic factors
	Relative risk	95% CI	p Value	Relative risk	95% CI	p Value
Lifestyle factors
Use of recreational drugs during pregnancy
No	1	–	0.486	1	–	0.495
Yes	1.27	0.65 to 2.51		1.27	0.64 to 2.50
Smoking status
Non-smoker	1	–	0.027	1	–	0.082
Gave up before pregnancy	0.86	0.67 to 1.09		0.93	0.72 to 1.20
Gave up in first trimester	1.07	0.73 to 1.56		1.12	0.76 to 1.66
Smoker during pregnancy	1.35	1.05 to 1.72		1.38	1.04 to 1.84
Alcohol use
Non-drinker	1	–	0.205	1	–	0.918
Gave up before pregnancy	0.83	0.66 to 1.04		1.02	0.78 to 1.34
Gave up in first trimester	0.78	0.61 to 0.99		0.98	0.73 to 1.31
Drank during pregnancy	0.86	0.66 to 1.13		1.08	0.79 to 1.48
Daily consumption of five fruit and vegetables
At least once a week	1	–	0.022	1	–	0.027
Never	1.31	1.04 to 1.64		1.31	1.03 to 1.66
Mediterranean diet factors
≥1	1	–	0.052	1	–	0.036
None	1.71	1.00 to 2.92		1.81	1.04 to 3.14
Socio-demographic factors
Mother's age (years)
<20				1	–	0.585
20–29				1.31	0.86 to 1.99
30–39				1.37	0.88 to 2.13
40+				1.32	0.71 to 2.45
Mother's educational level
Degree level and above				1	–	0.052
University-access level				1.29	1.00 to 1.66
Upper secondary qualification				1.36	1.06 to 1.76
No formal/lower secondary qualification				1.42	1.06 to 1.89
Mother's ethnicity
White				1	–	0.025
Mixed				1.70	0.97 to 2.99
Asian or Asian British				1.54	1.13 to 2.11
Black or Black British				1.36	0.89 to 2.08
Chinese or other ethnic group				1.99	0.87 to 4.55
Mother's BMI
20.0–24.9				1	–	0.001
<20				1.12	0.75 to 1.67
25.0–29.9				0.80	0.64 to 1.00
≥30				0.58	0.45 to 0.76
No pre-pregnancy weight recorded				1.07	0.57 to 2.02