Mean and SD of z-score of lung function measures adjusted for age, gender and height at age 8–9 years, with CIs for the difference of means (premature − term), unadjusted and adjusted for maternal smoking in pregnancy and social status
| 25–32 weeks (n=65) | Term (n=6144) | Difference (95% CI) (unadjusted) | Difference (95% CI) (adjusted) | p Value for adjusted analysis | |||
| Mean | SD | Mean | SD | ||||
| FEV1 | −0.461 | 0.876 | 0.011 | 1.000 | −0.472 (−0.716 to −0.228) | −0.487 (−0.791 to −0.184) | 0.002 |
| FVC | −0.204 | 0.950 | 0.005 | 1.001 | −0.209 (−0.453 to 0.035) | −0.151 (−0.454 to 0.152) | 0.329 |
| FEF25–75 | −0.573 | 0.928 | 0.013 | 1.001 | −0.586 (−0.829 to −0.342) | −0.627 (−0.930 to −0.325) | < 0.001 |
| FEV1/FVC | −0.362 | 1.183 | 0.009 | 0.997 | −0.371 (−0.617 to −0.125) | −0.488 (−0.793 to −0.182) | 0.002 |
| FEF25–75/FVC | −0.457 | 0.963 | 0.010 | 1.001 | −0.467 (−0.713 to −0.221) | −0.512 (−0.818 to −0.207) | 0.001 |
| 33–34 weeks (n=79) | Term (n=6144) | Difference and 95% CI (unadjusted) | Difference and 95% CI (adjusted) | p Value for adjusted analysis | |||
| Mean | SD | Mean | SD | ||||
| FEV1 | −0.498 | 1.094 | 0.011 | 1.000 | −0.509 (−0.733 to −0.285) | −0.485 (−0.724 to −0.246) | <0.001 |
| FVC | −0.313 | 1.036 | 0.005 | 1.001 | −0.318 (−0.540 to −0.096) | −0.352 (−0.589 to −0.115) | 0.004 |
| FEF25–75 | −0.425 | 1.095 | 0.013 | 1.001 | −0.438 (−0.659 to −0.217) | −0.434 (−0.670 to −0.197) | < 0.001 |
| FEV1/FVC | −0.312 | 1.169 | 0.009 | 0.997 | −0.320 (−0.545 to −0.096) | −0.239 (−0.477 to −0.001) | 0.049 |
| FEF25–75/FVC | −0.271 | 1.059 | 0.010 | 1.001 | −0.281 (−0.503 to −0.060) | −0.267 (−0.503 to −0.031) | 0.027 |
| 35–36 weeks (n=238) | Term (n=6144) | Difference and 95% CI (unadjusted) | Difference and 95% CI (adjusted) | p Value for adjusted analysis | |||
| Mean | SD | Mean | SD | ||||
| FEV1 | 0.008 | 0.908 | 0.011 | 1.000 | −0.003 (−0.133 to 0.127) | −0.012 (−0.147 to 0.123) | 0.867 |
| FVC | 0.015 | 0.950 | 0.005 | 1.001 | 0.010 (−0.120 to 0.139) | 0.009 (−0.125 to 0.143) | 0.893 |
| FEF25–75 | −0.010 | 0.879 | 0.013 | 1.001 | −0.023 (−0.152 to 0.106) | −0.034 (−0.168 to 0.099) | 0.616 |
| FEV1/FVC | 0.004 | 0.906 | 0.009 | 0.997 | −0.005 (−0.135 to 0.125) | −0.017 (−0.151 to 0.117) | 0.805 |
| FEF25–75/FVC | −0.022 | 0.925 | 0.010 | 1.001 | −0.033 (−0.162 to 0.097) | −0.037 (−0.171 to 0.096) | 0.582 |
FEF25–75, forced expiratory volume at 25–75% of FVC; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.