Table 3 Associations between maternal smoking during pregnancy and infant birthweight by maternal GSTT1 and GSTM1 genotype assessed by the crude and adjusted coefficient ß in linear regression
Genotype | Smoking status during pregnancy | Birthweight, g | Birthweight, g β+ crude (SE) P | Birthweight, g β++ adjusted (SE) P | Birthweight, g β++ adjusted (SE) P |
|---|---|---|---|---|---|
Total sample | Non-smoking (n = 456) | 3390.3 | Referent | Referent | Referent |
Smoking (n = 83) | 3284.1 | −86.5 (57.5) 0.066 | −83.4 (57.1) 0.073 | −83.4 (57.1) 0.073 | |
GSTT1 | Â | Â | Â | Â | Â |
Present | Non-smoking (n = 385) | 3401.4 | Referent | Referent | Referent |
Present | Smoking (n = 61) | 3320.7 | −70.4 (65.7) 0.143 | −72.3 (65.1) 0.134 | −38.8 (57.6) 0.250 |
Null | Non-smoking (n = 71) | 3330.0 | Referent | Referent | −22.6 (57.6) 0.345 |
Null | Smoking (n = 22) | 3182.9 | −115.9 (129) 0.186 | −123.7 (131) 0.175 | −162.9 (93.0) 0.041 |
*Interaction: smoking × GSTT1-null | −111.9 (123.1) 0.182 | −96.8 (122.5) 0.215 | |||
GSTM1 | Â | Â | Â | Â | Â |
Present | Non-smoking (n = 242) | 3413.6 | Referent | Referent | Referent |
Present | Smoking (n = 49) | 3255.9 | −87.2 (73.9) 0.119 | −85.1 (74.2) 0.126 | −58.8 (66.1) 0.187 |
Null | Non-smoking (n = 214) | 3363.9 | Referent | Referent | −32.4 (41.2) 0.216 |
Null | Smoking (n = 34) | 3324.8 | −97.1 (92.0) 0.146 | −100.6 (90.2) 0.133 | −118.7 (79.6) 0.069 |
*Interaction: smoking ×GSTM1-null | −17.0 (106.1) 0.437 | −26.6 (105.6) 0.400 | |||
GSTT1 & GSTM1 | Â | Â | Â | Â | |
Present | Non-smoking n = 207) | 3429.4 | Referent | Referent | Referent |
Present | Smoking (n = 38) | 3251.2 | −137.9 (82.3) 0.048 | −135.5 (82.6) 0.051 | −84.7 (71.2) 0.118 |
Null | Non-smoking (n = 36) | 3339.7 | Referent | Referent | 10.1 (76.1) 0.447 |
Null | Smoking (n = 11) | 3093.5 | −318.0 (198) 0.058 | −320.8 (203) 0.061 | −311.2 (128) 0.008 |
*Interaction: smoking ×GSTT1–null ×GSTM1–null | - 240.3 (164) 0.072 | −234.5 (164.3) 0.078 | |||