Table 2.

General and trimester-specific univariate associations of potential confounders and birth weight (grams; continuous variable)

	Effect size (βa)	95% CI	P valueb
General
Male sex of child	110.6	91.5, 129.7	<0.001
History of LBW	−464.5	−511.9, −417.1	<0.001
History of PTB	−317.4	−361.3, −273.4	<0.001
History of spontaneous abortion	31.4	7.6, 55.3	0.01
History of hypertension	6.7	−12.0, 25.4	NS
Hospitalisation during pregnancy	−103.3	−157.8, −48.8	<0.001
Parity	89.4	74.7, 104.0	NS
Home ownership	128.4	49.0, 207.8	<0.001
Marital status (married)	100.9	56.2, 145.6	<0.001
Maternal educational level	99.8	65.2, 134.5	<0.001
Maternal social economic status	−3.7	−9.9, 2.6	NS
Paternal social economic status	115.9	48.3, 183.4	<0.001
Maternal BMI (pre-pregnancy)	227.5	74.4, 380.6	<0.001
Paternal weight	1.4	0.2, 2.7	NS
Paternal height	3.5	1.4, 5.6	<0.001
Maternal age at LMP	−37.0	−61.6, −12.5	NS
Maternal age at delivery	−45.7	−70.3, 21.2	NS
Smoking before pregnancy	−99.6	−123.9, −75.4	0.001
Drug abuse	−189.5	−331.8, −47.2	<0.001
1st trimester
Smoking	−164.1	−186.7, −141.5	<0.001
Alcohol use	−265.0	−320.7, −209.3	0.01
2nd trimester
Smoking	−193.8	−168.2, −218.4	<0.001
Alcohol use	20.7	2.4, 39.1	0.008
Negative mood	−1.5	−3.6, 0.5	NS
Poor maternal health	1.6	−7.9, 11.2	NS
In paid work	−43.7	−64.8, −22.7	<0.001
Shift work	1.7	−12.8, 16.2	NS
Night shift	52.1	12.6, 91.5	0.01
3rd trimester
Smoking	−74.1	−134.4, −10.9	<0.001
Alcohol use	−217.7	−313.0, −125.7	<0.001
Negative mood	1.7	−0.3, 3.7	NS
Poor maternal health	10.2	−3.5, 23.9	NS
In paid work	−20.3	−43.2, 2.5	NS
Shift work	45.5	−10.3, 101.3	NS
Night shifts	71.6	7.5, 135.6	<0.001

CI confidence interval

^aBeta (regression coefficient)

^bStatistically significant P < 0.05