Acute fetal heart rate tracing changes secondary to cigarette smoking in third trimester pregnancies.

Objective: In this study, we aimed to assess the acute alterations on some features of fetal heart rate (FHR) tracings in third trimester pregnancies.

Methods: Data of FHR tracing records were obtained from 79 otherwise healthy pregnant women aged between 18 and 41. Among 79 women, 39 were nonsmokers while the remaining were chronic smokers (six or more cigarettes per day, with an average of 10 cigarettes per day). The baseline of tracings, the number of accelerations and decelerations of FHR, as well as the FHR mean, standard deviation, short-term variability of FHR were all calculated for each participant. The results of smokers and nonsmokers, then the results of smokers before and after smoking were compared.

Results: Comparison of some demographic and FHR tracing characteristics between smoker and nonsmoker groups indicated significantly decreased variability in smoker group. All FHR tracing characteristics were compared before and, immediately after cigarette smoking and revealed significantly higher mean baseline, lower variability and acceleration after smoking a cigarette.

Conclusion: Even in a short time period, smoking is associated with some changes in FHR monitorization characteristics, detailed analyses of these changes may clarify the pathophysiology of smoking associated perinatal outcome.