title: Quantitative effects of tobacco smoking exposure on the maternal-fetal circulation.
abstract: BACKGROUND
  Despite the existence of various published studies regarding the effects of tobacco smoking on pregnancy, and especially in regards to placental blood flow and vascular resistance, some points still require clarification. In addition, the amount of damage due to tobacco smoking exposure that occurs has not been quantified by objective means. In this study, we looked for a possible association between flow resistance indices of several arteries and the levels of urinary cotinine and the concentration of carbon monoxide in the exhaled air (COex) of both smoking and non-smoking pregnant women. We also looked for a relationship between those findings and fetal growth and birth weight.
  
  
  METHODS
  In a prospective design, thirty pregnant smokers and thirty-four pregnant non-smokers were studied. The volunteers signed consent forms, completed a self-applied questionnaire and were subjected to Doppler velocimetry. Tobacco smoking exposure was quantified by subject provided information and confirmed by the measurement of urinary cotinine levels and by the concentration of carbon monoxide in the exhaled air (COex). The weight of newborns was evaluated immediately after birth.
  
  
  RESULTS
  Comparing smoking to non-smoking pregnant women, a significant increase in the resistance index was observed in the uterine arteries (P = 0.001) and umbilical artery (P = 0.001), and a decrease in the middle cerebral artery (P = 0.450). These findings were associated with progressively higher concentrations of COex and urinary cotinine. A decrease in the birth weight was also detected (P < 0.001) in association with a progressive increase in the tobacco exposure of the pregnant woman.
  
  
  CONCLUSIONS
  In pregnant women who smoke, higher arterial resistance indices and lower birth weights were observed, and these findings were associated with increasing levels of tobacco smoking exposure. The values were significantly different when compared to those found in non-smoking pregnant women. This study contributes to the findings that smoking damage during pregnancy is dose-dependent, as demonstrated by the objective methods for measuring tobacco smoking exposure.
authors: Obstetrics, Sao Lucas Hospital da Pontificia Universidade Catolica do Rio Grande do Sul, Rio Grande do Sul, Porto Alegre, Brazil. juliamachado@terra.com.br
authors: Julia de B
authors: Jde B
authors: Machado
authors: V M
authors: VM
authors: Plínio Filho
authors: Guilherme O
authors: GO
authors: Petersen
authors: José M
authors: JM
authors: Chatkin
mesh_terms: D000328:Adult; D001724:Birth Weight / Q000187:drug effects; D002248:Carbon Monoxide / Q000032:analysis; D015331:Cohort Studies; D003367:Cotinine / Q000652:urine; D005260:Female; D005312:Fetal Blood / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology; D021041:Placental Circulation / Q000187:drug effects*; D011247:Pregnancy; D011446:Prospective Studies; D012212:Rheology; D057566:Self Report; D012907:Smoking / Q000009:adverse effects* / Q000652:urine; D018615:Ultrasonography, Doppler, Color; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000502:physiology; D055988:Uterine Artery / Q000000981:diagnostic imaging / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects*
chemical_list: D002248:Carbon Monoxide; D003367:Cotinine