Table 4.

Mediating effect of TD^a (mediating variable) on the association between MSDP^b (independent variable) and COPD^c (dependent variable) in smokers^d.

Path	β (SE)	P value
MSDP on COPDe	.123 (0.032)	<.001
MSDP on TDf	.050 (0.031)	<.001
TD on COPD given MSDPg	.059 (0.019)	.004
Indirect: MSDP on COPDh	.003 (0.002)	.03
Direct: MSDP on COPD given TDi	.120 (0.031)	<.001

^aTD: tobacco dependence.

^bMSDP: maternal smoking during pregnancy.

^cCOPD: chronic obstructive pulmonary disease.

^dAll analyses adjusted for age, sex, BMI, educational attainment, place of residence, ethnicity, occupation, childhood passive smoking, residential PM_2.5 exposure, history of childhood pneumonia or bronchitis, average annual household income, and medical history (coronary heart disease, hypertension, and diabetes).

^eCoefficients of independent variables on dependent variables after correction for covariates.

^fCoefficients of independent variables on mediating variables after adjustment for covariates.

^gCoefficients of mediating variables on dependent variables after correction for covariates and IVs.

^hIndirect effect of independent variables on dependent variables.

ⁱDirect effect of independent variables on dependent variables.