Table 2

Respiratory function results according to birth weight status, maternal smoking, and maternal occupation

NFEV0.4 (ml)FVC (ml)MEF25 (ml/s)FEV0.4/FVC
FEV0.4 = forced expired volume in 0.4 s; FVC = forced vital capacity; MEF25 = maximal expired flow at 25% of forced vital capacity; FEV0.4/FVC (%) = forced expiratory volume in 0.4 s as a proportion of forced vital capacity; CI = confidence interval.
*p<0.05; **p<0.01; ***p<0.001.
†n = 51 and n = 181 in manual and non-manual groups, respectively.
Birth weight status
Low birth weight for gestation98106 (26)121 (32)169 (64)0.87 (0.7)
Appropriate birth weight for gestation136126 (27)145 (34)196 (67)0.87 (0.6)
Difference (low − appropriate)−19−24−280
95% CI−26 to −12***−33 to −15***−45 to −11**−0.01 to 0.02
Maternal smoking in pregnancy
Yes95112 (31)131 (38)176 (68)0.87 (0.07)
No139121 (26)139 (33)191 (65)0.87 (0.06)
Difference (smoking − non-smoking)−9−8−150
95% CI−16 to −1*−17 to 1−33 to 2−0.02 to 0.01
Maternal occupation
Manual51106 (29)120 (36)172 (60)†0.88 (0.06)
Non-manual182121 (28)140 (34)188 (68)†0.87 (0.06)
Difference (manual − non-manual)−15−20−160.02
95% CI−23 to −6**−31 to −10***−37 to 5−0.003 to 0.04