Appropriateness of intrapartum fetal heart rate management and risk of cerebral palsy Paula J. Melone, DO, J.M. Ernest, MD, Michael D. O'Shea, Jr., MD, and Kurt L. Kiinepeter, MD
Winston-Salem, North Carolina Cerebral palsy affects 2 in 1000 infants in the United States, and the intrapartum period is frequently scrutinized as the etiologic source. In a matched group of 49 infants with cerebral palsy at 1 year of age and 49 controls, no difference in the incidence of inappropriate intrapartum fetal heart rate pattern management was detected. This supports the conclusions of others that the intrapartum period is an infrequent source of cerebral palsy. (AM J OSSTET GVNECOL 1991 ;165:272-7.)
Key words: Cerebral palsy, fetal heart rate patterns, intrapartum management Cerebral palsy is an infrequent event affecting 2 in 1000 infants in the United States. 1 Studies from the United States of births in the 1950s and 1960s2 and from Australia of births in the 1970s and 1980s 3 investigating antecedents of cerebral palsy concluded that most cases have no identifiable antecedent events during the intrapartum period. Other studies" 5 have shown slight or no reduction in cerebral palsy rates after the advent of electronic fetal monitoring, which also suggests that intrapartum events are infrequent causes of cerebral palsy. In reviewing the prenatal and intrapartum courses of 34 infants in whom cerebral palsy developed, Niswander et al. 6 found no association between substandard obstetric care or delayed reaction to apparent intrapartum asphyxia and the development of cerebral palsy. In spite of mounting evidence that cerebral palsy is rarely associated with or caused by intrapartum events, including the management of various patterns of the fetal heart rate (FHR), the intrapartum time period continues to be scrutinized as the likely source of many cases of cerebral palsy. This belief implies that appropriate intrapartum management of the FHR and its various patterns should rarely be associated with cerebral palsy. Because of concerns regarding the quality of intrapartum care and resultant cerebral palsy, we asked the following question: Do babies in whom cerebral palsy develops have a higher incidence of inappropriate intrapartum management of nonreassuring FHR patFrom the Departments of Obstetrics and Gynecology and Pediatrics, Bowman Gray School of Medicine of Wake Forest University. Presented as Official Guest at the Fifty-third Annual Meeting of the South Atlantic Association of Obstetricians and Gynecologists, Hot Springs, Virginia, january 27-30,1991. Reprint requests: j.M. Ernest, MD, Department of Obstetrics and Gynecology, Bowman Gray School of Medicine, 300 South Hawthorne Road, Winston-Salem, NC 27103. 616130394
272
terns than babies in whom cerebral palsy does not develop?
Material and methods A blind, retrospective review of intrapartum management and fetal monitor strips was conducted by two perinatologists (P.J.M. and J.M.E.) for 50 infants with a diagnosis of cerebral palsy at 1 year of age and 50 matched controls. The 100 infants studied were born between 1983 and 1989 at Forsyth Memorial Hospital in Winston-Salem, North Carolina. All study infants with cerebral palsy were chosen from a group of newborns who required neonatal intensive care and who were examined at 1 year of age by one author (K.L.K.). The diagnosis of cerebral palsy was based on the finding of a motor impairment, independent of other developmental impairments. Abnormalities of position and posture were ascertained during independent evaluations by a developmental pediatrician and a pediatric physical therapist. These evaluations occurred on the same clinic date. Occasionally, serial clinic evaluations over the first year of life were required to firmly establish the diagnosis of cerebral palsy. Abnormal tone was the predominant clinical finding. Involuntary movements were not observed because of the age of the children at diagnosis. A control infant was matched for each study infant by review of obstetric delivery logs and choosing the next newborn with matching maternal race, gestational age within 1 week, and birth weight within 225 gm. Only singleton pregnancies were reviewed. The presence of specific antepartum and intrapartum factors related to cerebral palsy 2 also was evaluated. The two perinatologists, who were blind to the subject'S status as a case or control, independently reviewed the intrapartum management and fetal monitor strip of each newborn and determined if specific nonreassuring FHR patterns were present and whether management was appropriate or inappropriate. If
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there was a discrepancy in their assessment of the appropriateness of care, the tracings were then reviewed by the perinatologists together, still blind as to whether the infant was a case or control newborn, to arrive at a consensus about appropriateness of care. All fetal monitor strips from each infant were reviewed, but only the 24 hours immediately preceding delivery was considered in the evaluations. A FHR tracing was considered nonreassuring when one or more of the following was present: (1) prolonged bradycardia, defined as >2 minutes of FHR 1 hour of late decelerations in >50% of contractions in the absence of uterine hypertonicity; (3) severe variable decelerations, defined as >20 severe variable decelerations «60 beats/min for >60 seconds' duration or >60 beats/min drop from baseline) during the course of labor. Appropriateness of care was modified from Niswander et al." No intervention was considered necessary in the intrapartum period when the following occurred: presence of reassuring FHR tracing with FHR accelerations and normal short-term beat-to-beat variability or presence of mild variable decelerations, < 1 hour of late decelerations, 1 hour in >50% of contractions-maternal oxygenation and repositioning, discontinuation of oxytocin augmentation when present, fetal scalp blood pH testing if decelerations persisted in spite of interventions, and prompt delivery if the nonreassuring pattern did not subside, particularly if short-term beat-to-beat variability was absent with a fetal scalp blood pH
Winston-Salem, North Carolina Cerebral palsy affects 2 in 1000 infants in the United States, and the intrapartum period is frequently scrutinized as the etiologic source. In a matched group of 49 infants with cerebral palsy at 1 year of age and 49 controls, no difference in the incidence of inappropriate intrapartum fetal heart rate pattern management was detected. This supports the conclusions of others that the intrapartum period is an infrequent source of cerebral palsy. (AM J OSSTET GVNECOL 1991 ;165:272-7.)
Key words: Cerebral palsy, fetal heart rate patterns, intrapartum management Cerebral palsy is an infrequent event affecting 2 in 1000 infants in the United States. 1 Studies from the United States of births in the 1950s and 1960s2 and from Australia of births in the 1970s and 1980s 3 investigating antecedents of cerebral palsy concluded that most cases have no identifiable antecedent events during the intrapartum period. Other studies" 5 have shown slight or no reduction in cerebral palsy rates after the advent of electronic fetal monitoring, which also suggests that intrapartum events are infrequent causes of cerebral palsy. In reviewing the prenatal and intrapartum courses of 34 infants in whom cerebral palsy developed, Niswander et al. 6 found no association between substandard obstetric care or delayed reaction to apparent intrapartum asphyxia and the development of cerebral palsy. In spite of mounting evidence that cerebral palsy is rarely associated with or caused by intrapartum events, including the management of various patterns of the fetal heart rate (FHR), the intrapartum time period continues to be scrutinized as the likely source of many cases of cerebral palsy. This belief implies that appropriate intrapartum management of the FHR and its various patterns should rarely be associated with cerebral palsy. Because of concerns regarding the quality of intrapartum care and resultant cerebral palsy, we asked the following question: Do babies in whom cerebral palsy develops have a higher incidence of inappropriate intrapartum management of nonreassuring FHR patFrom the Departments of Obstetrics and Gynecology and Pediatrics, Bowman Gray School of Medicine of Wake Forest University. Presented as Official Guest at the Fifty-third Annual Meeting of the South Atlantic Association of Obstetricians and Gynecologists, Hot Springs, Virginia, january 27-30,1991. Reprint requests: j.M. Ernest, MD, Department of Obstetrics and Gynecology, Bowman Gray School of Medicine, 300 South Hawthorne Road, Winston-Salem, NC 27103. 616130394
272
terns than babies in whom cerebral palsy does not develop?
Material and methods A blind, retrospective review of intrapartum management and fetal monitor strips was conducted by two perinatologists (P.J.M. and J.M.E.) for 50 infants with a diagnosis of cerebral palsy at 1 year of age and 50 matched controls. The 100 infants studied were born between 1983 and 1989 at Forsyth Memorial Hospital in Winston-Salem, North Carolina. All study infants with cerebral palsy were chosen from a group of newborns who required neonatal intensive care and who were examined at 1 year of age by one author (K.L.K.). The diagnosis of cerebral palsy was based on the finding of a motor impairment, independent of other developmental impairments. Abnormalities of position and posture were ascertained during independent evaluations by a developmental pediatrician and a pediatric physical therapist. These evaluations occurred on the same clinic date. Occasionally, serial clinic evaluations over the first year of life were required to firmly establish the diagnosis of cerebral palsy. Abnormal tone was the predominant clinical finding. Involuntary movements were not observed because of the age of the children at diagnosis. A control infant was matched for each study infant by review of obstetric delivery logs and choosing the next newborn with matching maternal race, gestational age within 1 week, and birth weight within 225 gm. Only singleton pregnancies were reviewed. The presence of specific antepartum and intrapartum factors related to cerebral palsy 2 also was evaluated. The two perinatologists, who were blind to the subject'S status as a case or control, independently reviewed the intrapartum management and fetal monitor strip of each newborn and determined if specific nonreassuring FHR patterns were present and whether management was appropriate or inappropriate. If
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Intrapartum FHR management and risk of cerebral palsy 273
there was a discrepancy in their assessment of the appropriateness of care, the tracings were then reviewed by the perinatologists together, still blind as to whether the infant was a case or control newborn, to arrive at a consensus about appropriateness of care. All fetal monitor strips from each infant were reviewed, but only the 24 hours immediately preceding delivery was considered in the evaluations. A FHR tracing was considered nonreassuring when one or more of the following was present: (1) prolonged bradycardia, defined as >2 minutes of FHR 1 hour of late decelerations in >50% of contractions in the absence of uterine hypertonicity; (3) severe variable decelerations, defined as >20 severe variable decelerations «60 beats/min for >60 seconds' duration or >60 beats/min drop from baseline) during the course of labor. Appropriateness of care was modified from Niswander et al." No intervention was considered necessary in the intrapartum period when the following occurred: presence of reassuring FHR tracing with FHR accelerations and normal short-term beat-to-beat variability or presence of mild variable decelerations, < 1 hour of late decelerations, 1 hour in >50% of contractions-maternal oxygenation and repositioning, discontinuation of oxytocin augmentation when present, fetal scalp blood pH testing if decelerations persisted in spite of interventions, and prompt delivery if the nonreassuring pattern did not subside, particularly if short-term beat-to-beat variability was absent with a fetal scalp blood pH
