Evaluation of the Fetal Heart Rate during Amniocentesis in Fetuses with Normal and Abnormal Karyotype

Abstract Introduction. We monitored the fetal heart rate (FHR) during amniocentesis in fetuses at 16-22 weeks of gestation and investigated whether an abnormal FHR was associated with chromosomal abnormalities. Methods. This prospective study involved 600 women at 16-22 weeks of gestation who underwent genetic amniocentesis. The FHR, expressed as beats for minute, was recorded before (FHR1), immediately after (FHR2) and 60 min after (FHR3) the invasive procedure. Structural malformations detected by ultrasound and multiple pregnancy were excluded from the study. Results. Chromosomal abnormalities have been diagnosed in 27 fetuses. Mean FHR decrease after amniocentesis has been observed in normal and in abnormal fetuses. The mean variation during amniocentesis was significant in both groups (P<0.01). The comparison between the mean FHR of the two groups showed no differences in FHR1 and FHR2 (P>0.05) but a significant difference in FHR3 (P<0.05). Conclusion. The FHR decreased after amniocentesis; the decrease was larger in chromosomally abnormal fetuses than in normal fetuses. This difference in heart rate reaction to amniocentesis might be due to cardiac defects or developmental delay associated with the abnormal karyotype.