ACUTE MATERNAL AND FETAL CARDIOVASCULAR EFFECTS OF CAFFEINE INGESTION

Little data exist regarding the acute maternal and fetal cardiovascula r effects of caffeine ingestion. The purpose of this study is assess t he cardiovascular effects of caffeine ingestion in pregnant subjects a nd their fetuses. We examined seven caffeine-naive gravidas longitudin ally at 25.7 (SE +/- 0.7) and 36.1 (+/- 0.7) weeks' gestation, before and after ingestion of a caffeine citrate solution (100 mg/m-2 body su rface area). Maternal pulse, blood pressure, fetal heart rate, and fet al heart rate accelerations were determined before and after caffeine ingestion. Uterine artery, fetal aorta, and umbilical artery flow velo city waveforms were examined at similar intervals. Significant before and after caffeine differences, regardless of gestational age, were no ted for maternal pulse (85.1 vs 74.2 beats/min), diastolic blood press ure (65.9 vs 73.8 torr), mean arterial blood pressure (81.5 vs 87.5 to rr), uterine artery systolic-to-diastolic (S/D) ratio (1.9 vs 2.4), fe tal heart rate (144.6 vs 135.4 beats/min), and fetal heart rate accele rations (1.6 vs 4.2 per 30 minutes). Differences for fetal aortic and umbilical artery S/D ratios were not significant with respect to caffe ine administration. Fetal aortic peak velocities increased with caffei ne (85.5 vs 130.2 cm/sec) and the increase was augmented with advancin g gestational age. We conclude that maternal ingestion of modest amoun ts of caffeine citrate in caffeine-naive subjects significantly affect s both the fetal and maternal cardiovascular systems.