FHR monitoring and perinatal mortality in high-risk pregnancies

European Journal of Obstetrics & Gynecology and Reproductive Biology, 44 (1992) 59-63

59

0 1992 Elsevier Science Publishers B.V. All rights reserved 0028-2243/92/$05.00 EUROBS 01283

FHR monitoring and perinatal mortality in high-risk pregnancies V. Ocak, C. Sen, F. Demirkiran, U. Colgar, F. 6$er and 6. Kilavuz Department of Obstetrics and Gynecology, Division of Perinatologv, Cerrahpasa Medical School, University of Istanbul, Turkey

Accepted for publication 27 September 1991

Summary The aim of the study was to evaluate the effect of the introduction, of fetal heart rate monitoring on perinatal mortality rates in high-risk pregnancies. Results were compared with the perinatal mortality rates published previously from our clinics. The study group consisted of 2165 high-risk pregnant patients. The perinatal mortality rate in the study group was 28.6%, and the corrected rate 15.9%. The rates were significantly lower in comparison with the total perinatal mortality rates in former years. We are convinced that fetal heart-rate monitoring resulted in a significant decrease in the perinatal mortality rate. Although the increased use of fetal monitoring cannot reduce perinatal mortality resulting from problems such as genetic disorders, this study shows improved outcomes for many high-risk conditions, in particular postmature pregnancies. Fetal heart rate monitoring; Perinatal mortality rate; Pregnancy, high-risk

Introduction Perinatal mortality rates are high in Turkey. One of the possible causes is the delay in the introduction of biophysical equipment such as cardiotocography and ultrasound to monitor fetal well-being. Neonatal intensive care units are also few in number and not well developed. The perinatal mortality rates in Cerrahpasa Medical Faculty were 67.9 in 1956-1970, 37.8 in 1971-1980 and 43.3 in 1981-1985 [l-3]. The perinatal mortality rates are still high in comparison with the figures commonly obtained in Western countries [3,4]. Modern fetal monitoring methods such as

Correspondence: Dr. V. Ocak, Dept. of Obstetrics and Gynecology, Division’ of Perinatology, Cerrahpasa Medical School, University of Istanbul, Turkey.

cardiotocography and ultrasonography are applied in high-risk pregnancies since 1978. The purpose of the current study was to evaluate the influence of fetal heart rate monitoring on perinatal mortality rates. The goal was to decrease Turkish national perinatal mortality rates by dissemination of these techniques. Materials and Methods Patient population 2165 high-risk patients were monitored between January 1978 to January 1988 in the Perinatology Division, Department of Obstetrics and Gynecology, Cerrahpasa Medical School, University of Istanbul. The youngest patient was 17 and the oldest 55 years old. Most of the patients were in the 20-28 age group. Table I shows the indications for antepartum testing. The material in-

60 TABLE I Primary test indications

Prolonged pregnancy Poor obstetric history Rh isoimmunization Maternal systemic disorders Hypertension in pregnancy Premature labor Others a

n

%

1697 99 80 79 72 35 103

18.4 4.6 3.7 3.6 3.3 1.6 4.6

a Suspected IUGR, IUGR, advanced maternal age, uterine malformation, consanguineous marriages, decreased fetal movement, oligohydramnios.

eluded 1697 pregnancies lasting longer than 42 weeks, although in 267 out of the 1697 prolonged pregnancies dates were not fully certain. These cases were managed according to the same protocol applied to prolonged pregnancies, since the gestational age of these uncertain cases was at least at term by ultrasonographic evaluation. The 99 cases with a poor obstetric history included previous stillbirth, repeated abortions, unexplained intrapartum and neonatal death and previous pre-eclampsia. Seventy-nine cases of maternal systemic disorders included diabetes mellitus, maternal cardiac disease, SLE, sickle cell disease and familial Mediterranean fever.

appointment for the next week. If a reactive pattern was not seen within 20 min, the fetus was stimulated with either abdominal palpation or by giving a glucose containing beverage to the mother. If accelerations were not seen within 40 min the pattern was accepted as nonreactive. If the result was nonreactive, oxytocin was administered according to a fixed protocol [6]. Oxytocin challenge test (OCT) was classified as negative, positive or equivocal according to the criteria published by Schifrin 171, irrespective of whether contractions were spontaneous or induced. All traces were interpreted by the same clinician. If OCT was negative, another appointment was given for the next week. When the OCT was positive, the patients were delivered by cesarean section after stimulation of lung maturation if pregnancy duration was less than 34 weeks. If an equivocal result was obtained, NST and OCT were repeated the next day. In the presence of prolonged bradycardia, moderate or severe deceleration in NST or OCT the patient’s obstetric management was the same as for the patients with a positive OCT. The fetal monitoring protocol is shown in Table II. The assessment of amniotic fluid volume was not included in the manage-

TABLE II Fetal heart rate monitoring protocol

Monitoring procedures

The nonstress test (NST) protocol of Rochard and Schifrin was applied to all high risk patients [5]. A Hewlett-Packard 8030A model cardiotocography was used for fetal heart rate (FHR) monitoring. Fetal heart rate tests were performed after meals. During the test the patients maintained in a semifowler position. If two or more FHR accelerations, exceeding an amplitude of 15 beats and with a minimum duration of 15 s occurred with fetal movements during a 10 min period, the nonstress test (NST) was considered reactive. Nonreactive NST was the failure to meet these criteria. NST was performed to all patients once a week, except in prolonged pregnancies and diabetic pregnancies. In these groups the test was performed twice a week. If a reactive pattern was found we sent the patient home and made an

NST Reactive 2 Weekly or twice a week (prolonged pregnancy, diabetes mellitus) -Negative

I

Until 44 weeks

Nonreactive

OCT 1,

Positive Estimatio i of lung maturation

I

Induction of labor C/S If failed two times C/S

61 TABLE III Causes of perinatal mortality n

%

Fetal anomalies Prematurity Fetal asphyxia Birth trauma Hydrops fetalis Cord prolapse D. Mellitus(uncontrolled) Abruptio placentae Eclampsia IUGR Unexplained

15 13

Total

62

6 4

3 3 2

24.2 21.0 11.3 9.1 6.5 4.8 4.8 4.8 3.2 1.6 8.1 100.0

ment protocol of postterm pregnancy. The patients with reactive NST were followed biweekly until 44 weeks of gestation when the labor was induced. Cesarean section was performed if the induction failed twice. Statistical analysis

Chi-square analysis was used in statistical evaluation. Results The overall perinatal mortality rate in the study group was 28.6% Causes of perinatal mortality have been summarized in Table III. If fetal abnormalities, hydrops fetalis, abruptio placenta and birth trauma were excluded, the corrected perinatal mortality rate was 15.9% (Table IV).

mortality rates are even seven-fold increased [8]. Fleischer et al. showed that the perinatal mortality rate was significantly lower in monitored high-risk patients than non-monitored [9]. However in prolonged pregnancies perinatal morbidity rates remain high even in the monitorized patients. For this reason we have focused our study especially on the patients with prolonged pregnancies and uncertain dates. Many studies have been published which compare NST versus OCT as the primary test [ 10,111. There are also several studies that show low perinatal mortality and morbidity rates if fetal condition has been monitored by means of assessment of the fetal biophysical profile [12-141. We preferred NST because it is a quick, easy, noninvasive test to perform. If the NST was reactive whatever the risk factor, the test was repeated after one week except in prolonged pregnancies and diabetic patients in which the test was applied twice weekly. Sixty-two percent of the patients were delivered vaginally and 33% by cesarean section. Our cesarean rate may appear to be high, but all patients reported in this paper demonstrated high-risk factors or had a poor obstetric history. Fleischer et al. showed that one third of the patients with prolonged pregnancy delivered by cesarean section due to fetal distress. One third of the neonates delivered with low Apgar scores originated from prolonged pregnancies [ll]. Table III shows the perinatal mortality rates for all high risk patients and Table IV shows the causes of mortality. The overall and corrected perinatal mortality rates of the study group were 28.6% and 15.9%, respectively. The perinatal mortality rate has been decreased following introduction of FHR monitoring. On the other hand

Discussion In recent years electronic fetal heart rate monitoring with NST and OCT has been the most important method to determine fetal well-being. In our department NST and OCT was introduced in 1978. As shown in Table I; most of the patients included in the study had prolonged pregnancies (78.4%). In case of a prolonged pregnancy perinatal mortality rates are two fold and neonatal

TABLE IV Perinatal mortality rates PNM rates

n/N

%

Crude Corrected

62/2165 34;2137

28.6 15.9

n, number of perinatal deaths. N, total number of cases.

62 TABLE V The studies on perinatal mortality rates in our clinic Studies

n/N

PNM rates

Top~uoglu et al. [l] 1956-1970

1989/29 252

67.9

858/22666

37.8

Ocak et al. [2] 1971-1980 Sen et al. [3] 1981-1985 Recent study 1978-1988

previous reports, which addressed both low- and high-risk pregnancies. In conclusion, we think that in a developing country like Turkey routine use of fetal heart rate monitoring in high-risk pregnancies can reduce perinatal mortality rates.

Acknowledgement 1342/23 995 62/2 165 a

43.3 a 28.6

a Only high-risk pregnancies. n = number of perinatal deaths. N, total number of cases. P < 0.05, between the groups of Ocak and recent study. P < 0.001, between the groups of Sen and recent study.

others factors such as better neonatal care, better obstetric care and social circumstances may have influenced the perinatal mortality rates. Other studies describe perinatal mortality rates varying form 9.6-11.1% and 3.34%, respectively, in various high risk groups [15,16]. The corrected perinatal mortality rate (15.9%) as published in this report appears acceptable, considering the high incidence of postterm pregnancies. There have been three previous reports on perinatal mortality rates from our department. The study of Topcuoglu et al. included nonmonitored low- and high-risk pregnancies with a perinatal mortality rate of 67.9% [l]. The study of Ocak et al. also included low- and high-risk pregnancies with a perinatal mortality rate of 37.8%, but all patients were nonmonitored until 1978 and some of them were monitored between 1978-1980 [2]. We have started FHR monitoring since 1978. The study of Sen et al. also included low- and high-risk pregnancies, monitored and nonmonitored with a perinatal mortality rate of 43.3% [31 (Table V>. In the previous studies, the overall perinatal mortality rates were 67.9, 37.8 and 43.3%, respectively. Although in the presented study only high risk pregnancies have been included, the overall perinatal mortality rate is lower than in the three

We are most grateful to Prof. Dr. H.P. Van Geijn for his advice and the corrections to the paper in the preparatory phase.

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7 8

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