IN-UTERO EXPOSURE TO CIGARETTE-SMOKING INFLUENCES LUNG-FUNCTION AT BIRTH

To avoid the possible confounding effects of postnatal exposure to tob acco smoke, we investigated possible effects of uterine tobacco smoke (UTS) exposure upon infant lung function shortly after birth, Infants with no major disease, in one maternity ward in Oslo, Norway, particip ating in a cohort study established in 1992/1993, were included in the present study (n=803). Exposure information, assessed as maternal act ive and passive smoking during pregnancy and other personal and enviro nmental factors, was obtained by questionnaire, Tidal flow-volume (TFV ) loops (n=802) and compliance (Crs) and resistance (Rrs) of the respi ratory system (n=663) were measured at a mean age of 2.7 days, In girl s, the TFV ratio (time to reach peak expiratory flow to total expirato ry time (tPEF/tE)), and Crs were significantly lower with active as we ll as passive maternal smoking compared to nonexposure to UTS. Respira tory rate and Rrs were not significantly influenced by UTS exposure, H owever, in linear regression analysis adjusted for confounding factors (including respiratory rate), tPEF/tE and Crs, but not Rn, were relat ed to maternal active but not passive daily smoking, One daily cigaret te corresponded to a change in tPEF/tE of -0.0021 (95% confidence inte rval (95% CI) -0.0040 to -0.0002) and a change in Crs of -0.026 mL.cmH (2)O (95% CI -0.045 to -0.007 mL.cmH(2)O). The decrease was 0.023 and 0.29, respectively, in infants of an average smoker, Maternal smoking during pregnancy adversely affected tidal flow-volume ratios in health y newborn babies, as well as the compliance of the respiratory system in girls, independently of the reduced body size also resulting from m aternal smoking.