Respiratory function among preterm infants whose mothers smoked during pregnancy

Am J Respir Crit Care Med. 1998 Sep;158(3):700-5. doi: 10.1164/ajrccm.158.3.9711057.


We examined whether the adverse effects of prenatal exposure to tobacco on lung development are limited to the last weeks of gestation by comparing respiratory function in preterm infants whose mothers had and had not smoked during pregnancy. Maximal forced expiratory flow (Vmax FRC) and time to peak tidal expiratory flow as a proportion of total expiratory time (TPTEF:TE) were measured prior to discharge from hospital in 108 preterm infants (mean [SD] gestational age, 33.5 [1.8] wk), 40 of whose mothers had smoked during pregnancy. Infant urinary cotinine was less than 4 ng/ml in those born to nonsmokers, but it was as high as 458 ng/ml in exposed infants (p < 0.0001). TPTEF:TE was significantly lower in infants exposed to tobacco in utero (mean [SD], 0.369 [0.109]) when compared with those who were not (0.426 [0.135]) (p <= 0.02). Vmax FRC was also reduced in exposed infants (mean [SD], 85.2 [41.7] ml/s versus 103.8 [49.7] ml/s) (p = 0.07). After allowing for sex, ethnic group, body size, postnatal age, and socioeconomic status, TPTEF:TE remained significantly diminished in infants exposed prenatally to tobacco (p < 0.05). Thus, impaired respiratory function is evident in infants born on average 7 wk prior to the expected delivery date, suggesting that the adverse effects of prenatal exposure to tobacco are not limited to the last weeks of pregnancy.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Black People
  • Body Constitution
  • Cotinine / urine
  • Embryonic and Fetal Development
  • Ethnicity
  • Female
  • Functional Residual Capacity / physiology
  • Gestational Age
  • Humans
  • Infant, Newborn
  • Infant, Premature / physiology*
  • Infant, Premature / urine
  • Lung / embryology
  • Male
  • Maximal Expiratory Flow Rate / physiology
  • Peak Expiratory Flow Rate / physiology
  • Pregnancy
  • Pregnancy Complications*
  • Prenatal Exposure Delayed Effects*
  • Respiration / physiology*
  • Sex Factors
  • Smoking / adverse effects*
  • Social Class
  • Tidal Volume / physiology
  • Time Factors
  • White People


  • Cotinine