title: The effect of cigarette smoking on fetal heart rate tracing during pregnancy.
abstract: OBJECTIVE
  The objective of this study is to investigate the alterations caused by smoking on the features of fetal heart rate (FHR) tracings as well as to make a comparison between pregnant smokers and pregnant women with intrauterine growth restriction (IUGR).
  
  
  METHODS
  A number of established features derived from linear and nonlinear fields were employed to study the possible influence of maternal smoking on FHR tracings. Moreover, correlation and measures of complexity of the FHR were explored, in order to get closer to the core of information that the signal of FHR tracings conveys. Data included FHR tracings from 61 uncomplicated singleton pregnancies, 16 pregnant smoker cases, and 15 pregnancies of women with IUGR.
  
  
  RESULTS
  The analysis of FHR indicated that some parameters, such as mutual information (P=0.0025), multiscale entropy (P=0.01), and algorithmic complexity (P=0.024) appeared decreased in the group of pregnant smokers, while kurtosis (P=0.0011) increased. The comparison between pregnant smokers and pregnant women with IUGR indicated a reduction in Hjorth complexity (P=0.039) for the former.
  
  
  CONCLUSIONS
  Smoking during pregnancy seems to induce differences in several linear and nonlinear indices in recordings of FHR tracings. This may be the consequence of an altered neurodevelopmental maturation possibly resulting from chronic fetal hypoxemia in cigarette-exposed fetuses.
authors.affiliation: .
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Spyridou
authors.affiliation: .
authors.forename: Ioanna
authors.identifier: http://orcid.org/0000-0001-8915-6658
authors.initials: I
authors.lastname: Chouvarda
authors.affiliation: .
authors.forename: Leontios
authors.identifier: http://orcid.org/0000-0002-9932-9302
authors.initials: L
authors.lastname: Hadjileontiadis
authors.affiliation: .
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Maglaveras
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000503:physiopathology; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D012907:Smoking / Q000009:adverse effects*; D055815:Young Adult
keywords: Cardiotocography; maternal smoking; nonlinear analysis; pregnancy