Table 2. Associations of maternal passive smoking during pregnancy, CYP1A1, and GSTs genotypes with risks of spontaneous PTD.
| Case (n = 198) | Control (n = 524) | Crude OR (95% CI) | ORa (95%CI) | P-value | |
| N. (%) | N. (%) | ||||
| Passive smokingduring pregnancy | |||||
| No | 101(51.0) | 369(70.4) | 1 | 1 | |
| Yes | 97(49.0) | 155(29.6) | 2.29 (1.63–3.20) * | 2.20 (1.56–3.12) | 0.000 |
| CYP1A1 Msp I | |||||
| TT | 73(36.9) | 212(40.5) | 1 | 1 | |
| TC/CC | 125(63.1) | 312(59.5) | 1.16 (0.83–1.63) | 1.15 (0.82–1.63) | 0.418 |
| CYP1A1 BsrD I | |||||
| AA | 95(48.0) | 290(55.3) | 1 | 1 | |
| AG/GG | 103(52.0) | 234(44.7) | 1.34 (0.97–1.87) | 1.30 (0.93–1.81) | 0.133 |
| GSTM1 | |||||
| Present | 97(49.0) | 275(52.5) | 1 | 1 | |
| Null | 101(51.0) | 249(47.5) | 1.15 (0.83–1.60) | 1.12 (0.80–1.57) | 0.515 |
| GSTT1 | |||||
| Present | 95(48.0) | 241(46.0) | 1 | 1 | |
| Null | 103(52.0) | 283(54.0) | 0.92 (0.67–1.28) | 0.97 (0.69–1.37) | 0.877 |
| GSTs | |||||
| Present | 137(69.2) | 386(73.7) | 1 | 1 | |
| Null | 61(30.8) | 138(26.3) | 1.25 (0.87–1.78) | 1.29 (0.89–1.87) | 0.182 |
a.
ORa adjusted for family income, maternal age, education level and prepregnancy BMI.
b.
GSTs “null” if both GSTM1 and GSTT1 “null”, GSTs “present” if either GSTM1 or GSTT1 “present”.