title: Effect of maternal smoking during pregnancy on passive respiratory mechanics in early infancy.
abstract: We studied the effect of prenatal maternal cigarette smoking on passive expiratory mechanics in 53 healthy infants tested early in infancy (mean +/- SD, 5.1 +/- 1.5 weeks). Maternal smoking was measured by: 1) questionnaire reports of the number of cigarettes smoked per day; and 2) urine cotinine concentrations (corrected for creatinine) at each visit. Respiratory system mechanics were assessed by the single-breath occlusion-passive-flow-volume maneuver. In ten infants born to smoking mothers the time constant of the respiratory system was 23% reduced [0.34 vs. 0.44 s; 95% confidence interval (CI), -45% + 1%; P = 0.06]. This was related to an estimated 13% decrease in respiratory system compliance (4.86 vs. 5.62 mL/cmH2O; 95%CI, -33% + 6%; P = 0.18) and a 10% reduction in respiratory system resistance (0.073 vs. 0.081 cm H2O/mL/s; 95%CI, -42% + 22%; P = 0.56). Functional residual capacity (FRC), measured by helium-dilution, was also decreased by 13% (78 vs. 90 mL; 95%CI, -27% + 0.3%; P = 0.06) in smoke-exposed infants. Forced expiratory flow rates at FRC obtained by thoraco-abdominal compression were reduced by 28% in infants of smoking mothers (VFRC, 99 vs. 138 mL/s; 95%CI, -54% + 2%; P = 0.04) as reported previously in a larger sample from this population. This study was limited by small numbers of infants exposed to smoking during pregnancy and by ethnic imbalance among the smoking-exposed and unexposed groups.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Channing Laboratory, Brigham and Women's Hospital, Boston, Massachusetts 02118, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Brown
authors.forename: J P
authors.initials: JP
authors.lastname: Hanrahan
authors.forename: R G
authors.initials: RG
authors.lastname: Castile
authors.forename: I B
authors.initials: IB
authors.lastname: Tager
mesh_terms: D000328:Adult; D016001:Confidence Intervals; D005260:Female; D005540:Forced Expiratory Flow Rates; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012129:Respiratory Function Tests; D012907:Smoking / Q000009:adverse effects* / Q000503:physiopathology; D013147:Spirometry; D011795:Surveys and Questionnaires; D014028:Tobacco Smoke Pollution / Q000009:adverse effects; D014797:Vital Capacity
chemical_list: D014028:Tobacco Smoke Pollution