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Inr J Gynecol Obstet, 1992, 39: 23-27 International Federation of Gynecology and Obstetrics

Assessment of fetal well-being: Fetal movement count versus non stress test S. Wilailak”, S. Suthutvoravuta, K. Chaturachinda”

P. Cherng-sa-adb, Y. Herabutyaa and

aDepartment of Obstetrics and Gynecology, Faculty of Medicine and bDepartment of Nursing, Ramathibodi Hospital, Mahidol Vniversity, &mgkok 10400 (Thailand)

(Received June 24th, 1991) (Revised and accepted April Ist, 1992)

Abstract

Introduction

In this prospective study, comparisons were made between the results of fetal movement count as performed by either the attending staff or by the patients using the non stress test (NST) . A total of 283 NSTs were performed in 200 patients who had singleton pregnancy of at least 32 weeks gestation with indications for assessment of fetal well-being. Fetal movement counts performed by the attending staff and by the patients were recorded on 241 and 170 occasions, respectively. The results showed that the best correlation between fetal movement count by the attending staff with NST was when the criteria of three or more fetal movements within 10 min was used. Likewise, the best correlation between fetal movement count by patients with NST was found when ten fetal movements within 2 h was used as a cut offpoint. The result of this study suggests the usefulness of fetal movement count performed either by attending staff or patients as a cheap and effective method of screening for goodfetal well-being in places where NST is not readily available and may also be used as a screening for patients prior to further evaluation.

Since the current maternal mortality rate has become acceptably low even in developing countries, emphasis has shifted towards assessing fetal well being. Much effort has been put into detection of fetuses at risk [l]. The non stress test (NST) using electronic fetal monitoring is a world-wide accepted method [2]. The equipment is, however, expensive, requiring expertise and, in many countries is not readily available. In 1973 Sadovsky and Yaffe [3] introduced the concept of using fetal movement to objectively assess fetal well-being. Subsequent studies confirmed the reliability of this daily fetal movement count as a mean for detecting impending fetal jeopardy and possible demise [4-91. Pearson [lO,l I] in 1977 introduced the ‘Cardiff count to ten chart’. Westgren et al. [12] and Arulkumaran et al. [13] studied the maternal perception of sound-provoked fetal movements and found a good correlation with NST. The aim of this study was to evaluate the correlation between fetal movement count as observed by trained observer and by the patients themselves with the NST. Materials and methods

Keywords: Fetal movement count; Positive and negative predictive value; Non stress test. 0020-7292/92/%05.00 0 1992 International

Federation of Gynecology and Obstetrics Printed and Published in Ireland

Between June and December 1988, patients Article

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Wilailak et al.

carrying singleton pregnancy with gestational age of more than 32 weeks requiring fetal well-being assessment were recruited. Assessment of fetal well-being consisted of three procedures carried out without the knowledge of the result of each other. The patient was asked to record her perception of fetal movement on the modified ‘Cardiff count to ten chart’ (Table 1) one day before coming to the clinic to undergo NST. Fetal movement count observed by a trained observer was performed by researchers on the same day when NST was done but the result of NST was unknown to them. Observers felt fetal movement by placing both hands on both sides of the patient’s abdomen and recorded the number of fetal movements or kicks over a IO-mm period. NST was performed on the Corometric electronic fetal monitor, model 115. The result of NST was either ‘reactive’ or ‘non reactive’ according to the criteria set by FIG0 in 1985 [14]. The sensitivity, specificity, positive predictive value and negative predictive value of the fetal movement count recorded by the patient and by the observer compared with the NST results were then calculated. An attempt was also made to identify the cut off criteria which the number of fetal movements observed in 10 min and the duration of time taken by the fetus to complete ten kicks, which would best correlate with reactive NST. The comparisons were made by using the chi-square test with the level of significance at P C 0.05.

RC!!dtS A total of 200 patients were recruited and 283 NSTs were carried out; 48 (16.9%) NST

were non reactive, 40 of which were done within 1 week prior to delivery. Two hundred and forty-one tests of fetal movement count by observers were done, 15 (6.2%) of which no movement was detected, 34 (14.1%) had l-2 kicks, 59 (24.5%) had 3-4 kicks and 133 (55.2%) had 5 or more kicks. One hundred and seventy tests of fetal movement count by patients were done, 113 (66.5%) of which 10 kicks were observed within 2 h, 45 (26.5%) and 12 (7.0%) had 10 kicks observed within 6 h and more than 6 h, respectively. The average number of hours necessary to achieve the 10 fetal movements in our population is 4.1 h. Table 2 shows indications for assessment of fetal well-being with hypertensive disorder in pregnancy, the most common, followed by decreased fetal movement and post-term. Table 3 shows the correlation in terms of sensitivity, specificity, positive and negative predictive values of the number of fetal movement counts perceived by the observer varying from one or more to five or more counts within 10 min as compared with the NST result. The result indicates that NST readings correlate best when three or more fetal movements were perceived in 10 min with the level of significance at P < 0.05. Similarly, Table 4 shows a correlation between number of hours which have been taken by the patients to complete the ten fetal movement count chart and NST. The result indicated that NST readings correlate best if the count to ten was completed within a 2-h period as shown by the sensitivity, specificity and predictive values within the level of significance at P C 0.05. There was no stillbirth in this series and

Table 1. The modified ‘Cardiff count to ten chart’ used in this study. Date

Starting time

Number of fetal movements

Time when ten counts were completed

Number of hours to complete ten counts

8-10-88

09:oo

MM

ll:oo

2

Int J Gynecol Obstet 39

Fetal movement count versus non stress test Table 2.

25

Indications for assessment of fetal well-being.

Indications

No.

%

Hypertensive disorders in pregnancy Decreased fetal movement Post term Static weight Previous fetal loss Suspected IUGR* Diabetes mellitus Hypertension with diabetes Hypertension with previous fetal loss Miscellaneous

111 61 38 18 16 10 6 10 7 6

39.2 21.6 13.4 6.4 5.1 3.5 2.1 3.5 2.5 2.1

Total

283

109.00

*IUGR = intrauterine growth retardation.

only one neonate (OSO) had an Apgar score of 2 at 5 min. Twenty-six (13%) were delivered with gestational age less than 37 weeks and 28 (14%) underwent cesarean section for fetal distress. Table 5 shows the outcome of pregnancy as related to the results of the last test prior to delivery. In cases of non reactive NST, 27.5% as compared with 33% if fetal movement count by observer was nil in 10 min and 7 1.4% if fetal movement count by patient was taken more than 6 h to complete 10 counts had cesarean section for fetal distress. Discussion The fetal movement count is a method of assessing fetal well being which is simple and

Table 3.

inexpensive. Developing countries may particularly benefit from a method which is independent of electronic equipment. If, as shown by this study, a good correlation exists between fetal movement counts and a reactive non stress test, then assessment of fetal well being becomes universally available. Developing countries as well as all low risk populations could benefit from this form of antenatal surveillance. In this study, we reduced the error in interpersonal variations by training the observer to use the same method of assessing the fetal movement count and calibrate the result of the count to be more or less similar. We used a lo-min period because this length of time is not too long and is an appropriate

Quality of fetal movement counts by observer when compared with NST result. Counts in 10 min

Sensitivity (%) Specificity (%) Positive predictive value (%) Negative predictive value (%)

(: : 226)

12 (n = 210)

14.6 96.5 46.2 83.8

55.8 88.4 51.1 90.2

(,‘= 192)

(?= 167)

(z= 133)

16.1 80.3 45.8 94.1 P c 0.05

79.1 63.6 32.9 93.3

81.4 62.6 32.1 93.9

Article

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Wilailak et al.

Table 4.

Quality of fetal movement counts by patient when compared with NST result. Hours for 10 counts

Sensitivity (%) Specificity (%) Positive predictive value (%) Negative predictive value (%)

12 (n = 170)

t.“= 164)

(“n= 163)

4 (n = 138)

2 (n = 113) 1. = 71)

3.6 97.9 25.0 83.7

7.1 97.2 33.3 84.1

10.7 97.2 42.9 84.7

42.9 96.5 70.6 89.5

85.7 89.3 76.8 47.9 42.1 23.5 96.5 95.8 P < 0.05

an accepted standard fetal well-being assessment method [2]. The results of this study suggest that fetal movement count recorded by either the patient or the observers bears some correlation with the results of NST. The negative predictive value is in the order of 94-97%. In other words, if the fetal movement count was considered to be good by both, then the NST reading will almost certainly be reactive. On the other hand, the positive predictive value is in the order of 42-46%. That is to say if the patients who were considered to have low fetal movement counts only half will have non reactive NST readings. We also found that if fetal movement counts were to be assessed by

time for use as a screening test. Other factors which may influende the movement of the fetus such as the time of the day and before or after meals were not considered important in this study because some studies showed that they had slight effects on the fetal movements [15,16]. Evaluation of fetal well-being assessment methods compared with fetal outcomes at birth such as stillbirth or live-birth would require a very large study population. Other fetal outcomes such as Apgar score and meconium-stained amniotic fluid were difficult to study because of many confounding factors. In this study we compared the results of fetal movement count with NST which is

Table 5.

Outcome of pregnancy related to the result of the last tests prior to deliveries.

Tests

Results

No.

APGAR score at 5 min 55

Gestational age at delivery (weeks)

r5 137

137

Cesarean section due to fetal distress

NST (N = 200)

Reactive Non reactive

160 40

1 (2.6%)

160 (100%) 39 (97.4%)

18 (11.25%) 8 (20%)

142 (88.75%) 32 (80%)

17 (10.6%) 11 (27.5%)

Fetal movement count by observer (N = 186) (Ricks in 10 minutes)

0 l-2 3-4 ~5

12 24 41 109

1 (9.1%) -

11 (90.9%) 24 (100%) 41 (100%) 109 (100%)

1 (8.3%) 7 (29.2%) 3 (7.3%) 8 (7.3%)

11 (91.7%) 17 (70.8%) 38 (92.7%) 101 (92.7%)

4 (33.3%) 3 (12.5%) 6 (14.6%) 13 (11.9%)

Fetal movement count by patient (N = 159) (Hours of 10 kicks)

2 6 26

111 41 >7

-

111 (100%) 41 (100%) 7 (100%)

10 (9.0%) 12 (29.3%) 1 (14.2%)

99 (91.0%) 29 (70.7%) 6 (85.8%)

11 (9.9%) 6 (14.6%) 5 (71.4%)

Int J Gynecol Obstet 39

Fetal movement count versus non stress test

the observer within a short period of 10 min then the best correlation with NST reading would be met if three or more counts were perceived. As for the fetal movement count recorded by the patients themselves the best correlation with NST reading would be if the ten movements were completed within 2 h. We would suggest that in practice NST may not be necessary in cases where the criteria set in this study is met thus the fetus can be considered to be healthy. Eggertsen and Benedetti [17] found in their study of the ‘Count to ten chart’ that it was well accepted by the patients. However, the method of fetal movement count by patient has its own limitation that it is being subjected to the patients reliability in perceiving fetal movements. Fetal movement counts as performed by a trained observer can overcome this problem but it is rather time consuming for the attending physicians. However, both methods are simple, cheap and can be used to screen patients who require fetal well-being assessment in antenatal clinic or at home, thus costly NST can be avoided, especially in developing countries where electronic fetal monitors are not readily available in all places. References Garite T: Antepartum fetal surveillance. Clin Obstet Gynecol 30: 8856, 1987. Keegan KA: The nonstress test. Clin Obstet Gynecol 30: 921, 1987. Sadovsky E, Yaffe N: Daily fetal movement recording and fetal prognosis. Obstet Gynecol 41: 845, 1973. Sadovsky B, Polishuk WZ: Fetal movement in utero. Obstet Gynecol 500:49, 1977. Neldam S, et al.: movements as an indicator of fetal wellbeing. Lancet June 7, 1222, 1980.

6 7

8

9

10 11 12

13

14 15 16

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Pearson JF, Weaver J: Fetal activity and fetal well-being: an evaluation. Br Med J 1: 1305, 1976. Liston RM, Cobar AW, Mennuti MT, Gabb SG: Antepartum fetal evaluation by maternal perception of fetal movement. Obstet Gynecol 60: 424, 1982. Hertags K, Roberts AB, Cooper D, Griffin DR, Campbell S: Maternal perception of fetal motor activity. Br Med J 2: 1183, 1979. Raybum WF, Mckean HE: Maternal perception of fetal movement and perinatal outcome. Obstet Gynecol 566: 161, 1980. Pearson JF: Fetal movements - a new approach to antenatal care. Nursing Mirror April 21: 49, 1977. Pearson JF: Fetal movement recording: a guide to fetal well-being. Nursing Ties Sept 20: 1639, 1979. Westgren M, Ahnstrom H, Nyman M, Ulmsten U: Maternal perception of sound-provoked fetal movements as a measure of fetal well-being. Br J Obstet Gynecol 94: 523, 1987. Arulkumaran S, Anandakumar C, Wong YC, Ratnam SS: Evaluation of maternal perception of sound-provoked fetal movement as test of antenatal fetal health. Obstet Gynecol 73: 182, 1989. Rooth G, Huch A, Huch R: Guidelines for the use of fetal monitoring. Int J Gynecol Obstet 25: 159, 1987. Birkenfeld A, Larifer N, Sadovsky E: Diurnal variation of fetal activity. Obstet Gynecol 55: 417, 1980. Patrick J, Campbell K, Carmichel L, Natale R, Richardson B: Patterns of gross fetal body movements over 24hour observation intervals during the last 10 weeks of pregnancy. Am J Obstet Gynecol 142: 363, 1982. Eggertsen SC, Benedetti TJ: Maternal response to daily movement counting in pregnancy care settings. Am J Perinatol 4: 327, 1987.

Address for reprints:

s. wilailak Departmentof Obstetrics and Gynecology Faculty of Medicine, Ramathibndi Hospital M&idol University, Bangkok 10400,‘hiland

Article

Assessment of fetal well-being: fetal movement count versus non stress test.

In this prospective study, comparisons were made between the results of fetal movement count as performed by either the attending staff or by the pati...
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