Influence of nicotine chewing gum on fetal blood flow.

Several studies have shown that smoking is not beneficial to the fetus. Among the acute effects, influence on fetal circulation has been reported. Nicotine is considered to be one of the active agents in cigarette smoke. To test the nicotine effects on the human fetus, maternal and fetal cardiovascular dynamics were studied in 20 pregnant women when chewing a chewing gum containing 4 mg of nicotine and a chewing gum without nicotine given in a randomized double blind order. The fetal blood flow was measured with a method combining real-time ultrasonography and pulsed Doppler technique. Registrations were made in ten fetuses from the thoracic part of the descending aorta and in ten fetuses from the intra-abdominal part of the umbilical vein. In 15 of the fetuses registrations were also made from the umbilical artery. Concentrations of nicotine in plasma were analyzed in six women. The maternal plasma nicotine concentrations increased after the nicotine gum to a maximum value of 12.4 ng X ml-1 (median) at 25 min (figure 1). The 4 mg nicotine gum increased significantly maternal heart rate, systolic and diastolic blood pressure (figure 2). There was no influence on fetal heart rate or fetal blood flow, neither in the thoracic part of the descending aorta, nor in the intra-abdominal part of the umbilical vein (figure 3). There were no changes in the waveforms of the maximum blood velocity curves, neither of the aorta nor the umbilical artery. This indicates that there was no increased resistance in the placenta, neither after the nicotine gum nor the placebo gum.(ABSTRACT TRUNCATED AT 250 WORDS)