Roger K. Freeman

A prospective multi-institutional study of antepartum fetal heart rate monitoring

Abstract A total of 18,517 antepartum fetal heart rate (AFHR) monitoring studies were conducted on 7,448 high-risk patients in 18 institutions in the United States between 1976 and 1980. Data were gathered prospectively. A perinatal mortality rate of 12.9/1,000 (5.5/1,000 corrected) with a fetal death rate of 3.2/1,000 (1.9/1,000 corrected) was found. Nonreactive nonstress tests and nonreactive positive contraction stress tests were associated with significantly increased morbidity and mortality. When patients were ranked by “worst test result,” the presence of persistent late decelerations (positive contraction stress test) appeared to be an earlier warning sign of fetal deterioration than did the loss of reactivity.

A prospective multi-institutional study of antepartum fetal heart rate monitoring: II. Contraction stress test versus nonstress test for primary surveillance☆

This study includes, 1,542 patients who underwent nonstress tests (NSTs) for primary fetal surveillance and 4,626 patients who underwent contraction stress tests (CSTs) for primary fetal surveillance. All pregnancies were at increased risk for uteroplacental insufficiency. The results showed that the two groups were comparable according to maternal diagnostic criteria for testing. Those patients who underwent NSTs as primary surveillance had a 2.9% incidence of intervention because of abnormal test results while the CST group had a 4.5% incidence of intervention because of abnormal test results ( p less than 0.05). The NST group had significantly more respiratory distress syndrome, intrauterine growth retardation, birth weight less than 2,500 gm, and 5-minute Apgar scores less than 7. The antenatal death rate was nearly eight times higher in the NST group (7.8/1,000 versus 1.1/1,000 in the CST group) (p less than 0.05). After correction for congenital anomalies and unrelated causes, the NST group had an antenatal death rate of 3.2/1,000 versus 0.4/1,000 in the CST group (p less than 0.05); there was still an antenatal death ratio of 8:1.

Sinusoidal fetal heart rate pattern: Its definition and clinical significance

A review was made of the available literature on the sinusoidal heart rate (SHR) pattern. A specific definition of SHR was made in order to elucidate its clinical significance. According to this definition 41 tracings from 23 publications were classified as being either true SHR, equivocal, or a heart rate pattern other than SHR. On the basis of this definition, 27 tracings were classified as true SHR patterns and all were associated with significant fetal or neonatal morbidity or mortality, except in two cases after administration of alphaprodine. Three tracings were judged to be equivocal. In two other cases the fetal heart rate tracings were classified as nonsinusoidal premortem patterns associated with poor perinatal outcome. As for the other nine tracings that did not meet the proposed definition, the perinatal outcome was normal. Therefore, because of a stricter definition of jeopardy, except when the SHR pattern appears after induction of analgesia with alphaprodine.

A randomized trial of ritodrine tocolysis versus expectant management in patients with premature rupture of membranes at 25 to 30 weeks of gestation

Expectant management was compared with similar management plus ritodrine tocolysis in a randomized controlled trial in patients with premature rupture of membranes at 25 to 30 weeks of gestation. In the tocolysis group intravenously administered ritodrine was instituted at the onset of labor and then changed to the oral form if successful. Tocolysis was discontinued or not instituted after 31 weeks of gestation. Seventy-nine patients were randomized over a 4-year period, 39 in the tocolysis group and 40 in the expectant group. Twenty-three patients in the tocolysis group actually received ritodrine. No difference between the two groups was demonstrated in the interval between premature rupture of membranes and delivery or in reaching 32 weeks of gestation. No statistical difference was seen in maternal morbidity. Birth weights and gestational ages at delivery were similar between the two groups as were the incidences of neonatal morbidities caused by prematurity and infection and in the duration of neonatal hospital stays. Despite being conducted in those gestational ages in which prolongation of pregnancy might be expected to be of most benefit, no difference could be demonstrated with the addition of tocolytic therapy over expectant management alone.

Prophylactic intrapartum amnioinfusion in patients with preterm premature rupture of membranes

Patients with preterm premature rupture of the membranes are at increased risk to develop intrapartum variable decelerations and fetal distress. Short-term saline solution amnioinfusion may be of benefit in the treatment of variable or prolonged decelerations once they appear. In an effort to assess the benefit of prophylactic amnioinfusion, patients with preterm premature rupture of the membranes were studied during a 1-year period in a prospective randomized manner. Patients receiving prophylactic amnioinfusion had significantly decreased incidence and severity of variable decelerations in the first stage of labor (p less than 0.005). In the second stage of labor, the incidence of severe (p less than 0.005) and total (p less than 0.001) decelerations was also decreased in the treatment group. The umbilical arterial pH at delivery was significantly lower (p less than 0.001) as was the umbilical venous pH (p less than 0.005) in the newborn infants of control patients compared with those of patients receiving amnioinfusion. This suggests that prophylactic intrapartum amnioinfusion is of significant benefit in reducing the incidence of variable decelerations and improving the metabolic state in newborn infants born to women with preterm premature rupture of the membranes.

Intrapartum management of category II fetal heart rate tracings: towards standardization of care

There is currently no standard national approach to the management of category II fetal heart rate (FHR) patterns, yet such patterns occur in the majority of fetuses in labor. Under such circumstances, it would be difficult to demonstrate the clinical efficacy of FHR monitoring even if this technique had immense intrinsic value, since there has never been a standard hypothesis to test dealing with interpretation and management of these abnormal patterns. We present an algorithm for the management of category II FHR patterns that reflects a synthesis of available evidence and current scientific thought. Use of this algorithm represents one way for the clinician to comply with the standard of care, and may enhance our overall ability to define the benefits of intrapartum FHR monitoring.

Quantitation of uterine activity preceding preterm, term, and postterm labor

To assess uterine activity before labor in patients delivering preterm, at term, and postterm, the maximum spontaneous contraction frequency per 10-minute window during the initial portion of antepartum fetal heart rate monitoring was analyzed. Patients with multiple gestation, third trimester bleeding, polyhydramnios, or premature rupture of membranes and those already diagnosed with preterm labor were eliminated from the study. Of the 2446 remaining patients (7247 antepartum fetal heart rate tests) who went into spontaneous labor, 237 did so before 37 completed weeks of gestation, 1077 entered labor at term (38 to 42 completed weeks), and 1132 did so after 42 weeks. There was a significant increase in maximum uterine activity per 10-minute window from 30 to 44 weeks of gestation (average 4.7% per week; r = 0.97, p less than 0.0001). When compared with patients delivering spontaneously at term, average maximum uterine activity per 10-minute window was greatest in the preterm labor group (p less than 0.05) and least in the postterm labor group (p less than 0.05). These differences were present for several weeks preceding the onset of spontaneous labor. All three groups showed a surge of uterine activity during the 3 days before the onset of spontaneous labor.

The significance of a previous stillbirth

Among 7052 patients studied between 1976 and 1982 in a collaborative project on antepartum fetal heart rate monitoring, 337 patients had a previous stillbirth as a reason for testing. Overall a previous stillbirth history significantly increased the risk of having a positive result on a contraction stress test, primarily among hypertensive patients. Patients with a previous stillbirth also had a significantly higher incidence of respiratory distress syndrome in their neonates attributable to premature intervention for maternal indications (primarily among hypertensive women and patients with clinical intrauterine growth retardation). Low Apgar scores were found to be significantly increased in diabetics with previous stillbirths primarily due to neonates with congenital malformations. Premature intervention by labor induction or cesarean section was more common among patients with a previous stillbirth for both maternal indications and abnormal antepartum fetal heart rate studies. Previous stillbirth would appear therefore to be a significant risk factor primarily when associated with a diagnosis of hypertension or clinical intrauterine growth retardation.

Signal ambiguity resulting in unexpected outcome with external fetal heart rate monitoring

We report cases of unexpected adverse fetal outcome from monitored labors in which the fetal heart rate tracing was interpreted as reassuring. In these cases, portions from another signal source, usually maternal, were imperceptibly substituted into the fetal tracing in a way that masked the evidence of fetal compromise.

Antepartum surveillance for a history of stillbirth: When to begin?

OBJECTIVE A history of stillbirth is universally accepted as an indication for antepartum fetal heart rate testing. Our goal was to examine when fetal testing should begin in an otherwise healthy patient with a history of stillbirth. STUDY DESIGN This is a nonconcurrent cohort study of patients who were seen for antepartum surveillance from January 1979 to December 1991 with a history of stillbirth as the only indication for testing. Subsequent pregnancies were evaluated for adverse outcomes and abnormal antepartum test results. RESULTS There was one case of recurrent stillbirth among the 300 study patients. Nineteen patients (6.4%) had one or more positive antepartum surveillance tests (positive contraction stress test or biophysical profile < or = 4). Three patients (1%) had positive tests before 32 weeks, all of whom were subsequently delivered without incident at term. Three patients were delivered for positive tests at < 36 weeks, one by cesarean section for fetal distress. We could not detect a relationship between the gestational age of the previous stillborn and the incidence of abnormal tests or fetal distress in subsequent pregnancies. CONCLUSION Antepartum surveillance should begin at > or = 32 weeks in the healthy pregnant woman with a history of stillbirth.