Nicotine and caffeine. Influence on prenatal hemodynamics and behavior in early twin pregnancy.

To evaluate the effect of nicotine and caffeine in early multiple pregnancies. Ten women with twin pregnancies volunteered to take part in the study. Five mothers smoking > 5 cigarettes/d were investigated before and after smoking. Five women were investigated before and after drinking coffee. Maternal hemodynamics, umbilical blood flow, fetal heart rate and twin behavior were longitudinally documented during a 30-minute session from 8 to 16 gestational weeks. Fetal behavior was analyzed from videotapes using a one-minute window. The mean increase in maternal heart rate after smoking was 10 bpm (P < .005). After drinking coffee, it was 8 bpm (P < .01). The pulsatility index of the umbilical artery showed a significant increase after smoking (P < .01). After coffee the increase was also significant (P < .05). Two of five behavioral parameters (swallowing and breathing) demonstrated significant changes after the consumption of coffee (P < .001). This pilot study demonstrated significant effects of nicotine and caffeine consumption on maternal and fetal hemodynamics. It seems worthwhile to study the influences of smoking and coffee consumption on early twin behavior in larger samples.