Associations between maternal smoking and children's asthma and FEF25–75 according to maternal and child GSTT1-null genotypes
| GSTT1 | Asthma | FEF25–75 | ||||||||
| Mother | Child | N | Cases (%) | OR | (95% CI) | p Value | N | AM difference | (95% CI) | p Value |
| + | + | 2577 | 331 (12.8) | 1.05 | (0.93 to 1.19) | 0.43 | 2313 | −0.05 | (−0.09 to −0.00) | 0.03 |
| + | − | 349 | 40 (11.5) | 1.15 | (0.77 to 1.71) | 0.48 | 296 | 0.04 | (−0.09 to 0.18) | 0.51 |
| − | + | 340 | 47 (13.8) | 1.19 | (0.85 to 1.68) | 0.31 | 313 | −0.02 | (−0.15 to 0.11) | 0.77 |
| − | − | 242 | 29 (12.0) | 0.70 | (0.45 to 1.10) | 0.13 | 202 | 0.00 | (−0.17 to 0.18) | 0.96 |
AM, arithmetic mean; FEF25–75, maximal mid expiratory flow; +, one or more copies of GSTT1; −homozygous deletion of GSTT1.