Fetal heart rate evolution patterns associated with umbilical cord abnormalities in term fetuses: a single center...

This study aimed to estimate population-based frequencies of various fetal heart rate (FHR) evolution patterns in cases with umbilical cord abnormalities and to identify particular FHR evolution patterns associated with different types of umbilical cord abnormalities.

We conducted a retrospective cohort study. FHR evolution patterns, evaluating the trend of all FHR tracings from admission to delivery, were retrospectively analyzed and classified into five categories: persistent non-reassuring (p-NR), persistent bradycardia, Hon's pattern, reactive-prolonged deceleration (PD), and persistent reassuring. The study included pregnant women who delivered after 37 weeks of gestation. Frequencies of the five FHR evolution pattern categories were stratified by the type of umbilical cord abnormalities.

Among 1,195 participants, 1,074 had no cord abnormalities, and 122 had abnormalities. Overall, the prevalence of FHR patterns in cases with the cord abnormality was: 2% p-NR, 3% Hon's pattern, 21% reactive-PD, and 74% persistent reassuring. The frequencies of various FHR evolution patterns did not differ significantly between cases with and without umbilical cord abnormalities. However, when analyzing specific cord abnormalities, velamentous cord insertion showed a higher prevalence of p-NR (7% vs. 1%, p = 0.14) and reactive-PD (40% vs. 17%, p < 0.05) compared with cases without cord abnormality, along with a lower prevalence of persistence reassuring patterns (53% vs. 79%, p < 0.05).

Analysis of FHR evolution patterns in a population-based sample demonstrated a higher occurrence of reactive-PD patterns in cases with umbilical cord abnormalities, which result in sudden deterioration of fetal condition during delivery, compared with cases without umbilical cord abnormalities.