Objective: To assess the effects of chorionic villus sampling (CVS) on fetal heart rate (FHR).
Methods: A prospective longitudinal study was conducted among 300 patients undergoing transabdominal CVS between 8 and 13 weeks of gestation. Duration of the procedure, number of needle passes, sample weight, maternal age, fetal gender, and FHR response to CVS were recorded.
Results: The FHR before but not after CVS was inversely correlated with gestational age (r = -0.406, p < 0.001). Conversely, following CVS, no correlation was observed between FHR and gestational age (r = -0.06, p = 0.27). The difference between FHR after CVS and that obtained before CVS (delta FHR) increased with increasing gestational age at sampling (r = 0.372, p < 0.0001), decreased with increasing specimen weight (r = -0.16, p = 0.01) and increased with increasing maternal age (r = 0.22, p < 0.0001). Duration of the procedure, fetal gender and number of needle passes did not affect delta FHR. Multiple logistic regression indicated that gestational age at CVS and maternal age but not the other variables significantly affected delta FHR and together they accounted for over 22% of the variance (R(2) = 0.224, p < 0.0001).
Conclusions: In summary, our results suggest that acute fetal hemodynamic changes accompany CVS and that these changes vary with gestational age.