Objective: We investigated the correlations between abnormal fetal heart rate (FHR) during the second stage of labor and delivery types and intrapartum maternal complications and fetal outcome.
Methods: The data of 232 nulliparas with single vertex in the second stage of labor (111 cases with normal FHR, 121 cases with abnormal FHR) were analyzed retrospectively.
Results: The incidence of abnormal FHR in the second stage of labor was 52.2% (121/232). The patterns of abnormal FHR included: 81 (66.9%) cases with moderate and/or severe variable deceleration (VD), 27 (22.3%) cases with scattered late deceleration (LD), only one with continuous LD, 4 (3.3%) cases prolonged deceleration (PD), 2 (1.7%) cases with VD and LD, 3 (2.5%) cases with VD and PD, 4 (3.3%) cases with diminished baseline variability. There were 13 (11.7%) among the cases with normal FHR and 35 (28.9%) among the cases with abnormal FHR underwent assistant delivery operations (forceps or/and vaccum), respectively (P < 0.05). Furthermore 29 of 35 (82.9%) cases underwent assistant operations for vagina delivery due to abnormal FHR, the others underwent assistant operations for vagina delivery due to weak expulsive force or malpositioning of fetal head. There was one case of complicated vaginal laceration in the group with abnormal FHR. There was no difference of newborns with low Apgar score between two groups.
Conclusions: There was a very high incidence of abnormal FHR during the second stage of labor, however, the most cases were response to parasympathetic stimulation due to umbilical cord or fetal head compression by mothers over push and descent of fetal head, or temporal diminishing of uterine placenta blood flow. It suggests that it is unnecessary to interfere immediately, unless truly fetal distress.