AUST.AND N.Z. JOURNAL OF ORSTETRICS AND GYNAECOLCGY
(7,8,13)and may represent exposure to cigarette smoke in the air. Further, in our study, excretion of nicotine metabolites in the urine rose with gestation suggesting possible alterations in nicotine metabolism with increasing gestation. The toxic effects of the constitutents of cigarette smoke on the fetus have been reviewed elsewhere (1). The intake of noxious substances from cigarette smoke depends not only on the number of cigarettes smoked but also on the puffing and inhaling patterns. Consequently, the number of cigarettes accounts for only about 25% of the variance in urinary cotinine, expired carbon monoxide and serum thiocyanate (14).Haddow et al(8) found serum cotinine to be a good predictor of low birth-weight and better than a history of smoking. In the present study, nicotine metabolites in urine (expressed as pg of cotinine/mg urinary creatinine) were estimated and compared with self-reports of smoking in determining birth-weight. Cotinine had significant negative correlation with birth-weight and adjusted birth-weight percentile, the association being stronger between cotinine level and birth-weight than between self-reported smoking and birthweight. Further in this study, self-reported active and passive smoking accounted for 43% of the variation in urinary cotinine levels (R2=0.434)which is higher than reported earlier (14). Our findings suggest that urinary cotinine assays may be used as part of tests in early pregnancy to assess exposure to tobacco smoke and to monitor the effectiveness of antismoking advice in the antenatal period.
References 1. Stillman RJ, Rosenberg MJ, Sachs BJ. Smoking and reproduction. Fertil Steril 1986; 46545-566. 2. Martin TR, Bracken ME. Association of low birth-weight with passive smoke exposure in pregnancy. Am J Epidemiol 1986; 124: 633-642. 3. Rubin DH, Krasilnikoff PA, Leventhal JM, Weile B, Berget A. Effect of passive smoking on birthweight. Lancet 1986; 2415-417. 4. Gillies PA, Wilcox B, Coates C, Kristmundsdottir F, Reid DJ. Use of objective measurement in validation of self reported smoking in children aged 10-11 years: salivary thiocyanate. J Epidemoil Comm Health 1982; 36:205-208. 5. Wilcox RG, Hughes J, Roland J. Verification of smoking history in patients after infarction using urinary nicotine and cotinine measurements. Br Med J 1979; 2 1026-1028. 6. Sillett RW, Wilson MB, Malcolm RE, Ball KP. Deception among smokers. Br Med J 1978; 2:1185-1186. 7. Benowitz N, Kuyt F, Jacob P, Jones R, Osman A. Cotinine disposition and effects. Clin Pharmacol Ther 1983; 34:604-611. 8. Haddow JE, Knight GJ, Palomaki GE, Kloza EM, Wald NJ. Cigarette consumption and serum cotinine in relation to birthweight. Br J Obstet Gynaecol 1987; 94:678-681. 9. Peach H, Ellard GA, Jenner PJ, Morris RW. A simple, inexpensive urine test of smoking. Thorax 1985; 40:351-357. 10. Altman DG, Coles EC. Nomograms for precise determination of birth-weight for dates. Br J Obstet Gynaecol 1980; 87:81-86. 11. Butler NR, Goldstein H, Ross EM. Cigarette smoking in pregnancy: its influence on birth-w&ht and perinital mortality. Br Med J 1972; 2:127-130. 12. Murphy JF, Dmmm JE, Mulcahy R, Daly L. The effect of maternal cigarette smoking on fetal birthweight and on growth of the fetal biparietal diameter. Br J Obstet Gynaecol 1980; 87:462-466. 13. Wald NJ, Boreham J, Bailey A, Ritchie C, Haddow JE, Knight G. Urinary cotinine as marker of breathing other peoples’ tobacco smoke. Lancet 1984; 1:230-231. 14. Vesey CJ, Saloojee Y, Cole PV, Russell MAH. Blood carboxyhaemoglobin, plasma thiocyanate and cigarette consumption: implications for epidemiological studies in smokers. Br Med J 1982; 2841516-1518.
Awt NZ J Obstet Gynaecol 1990; 3 0 36
Domiciliary Fetal Monitoring in a District Maternity Unit Kate H. Moore’, MRCOG, MRACOG and Richard Sillz,MRCOG Hull Maternity Hospital, Hull, England
Summary: Domiciliary Fetal Monitoring is a new technique which allows fetal heart rate monitoring from within a patient’s home. The 30 minute cardiotocograph is transmitted by telephone, to a central labour ward computer, within 45 seconds. Of 522 domiciliary cardiotocographsperformed on 100 consecutive patients, 356 (68%) were performed for suspected intrauterine growth retardation or reduced fetal movements. Thirty one (5.9%) recordings were abnormal; a repeat cardiotocograph in hospital was abnormal in 9 cases (1.3%); all such patients were delivered within 7 days. The induction rate for the study group was increased by a factor of 3.2 with respect to all hospital confinements; 49% of infants were small for gestational age (< 10th percentile). Caesarean section and forceps delivery rates were the same for both groups. No stillbirths occurred in the study group. After the introduction of domiciliary monitoring, the number and duration of hospital admissions for fetal surveillance were reduced by 29% and 52% respectively.
1. Registrar in Obstetrics and Gynaecology. 2. Senior Registrar in Obstetrics and Gynaecology.
Address for correspondence: Dr KH Moore, Lecturer, University Department of Obstetrics and Gynaecology, Royal Liverpool Hospital, Liverpool, England L7 8XP.
KATEH. MOOREAND RICHARDSILL
Patients were equally as able as midwives to perform domiciliary fetal monitoring. A patient survey revealed widespread satisfaction with the DFM system. Antenatal fetal heart rate monitoring has become an established means of fetal surveillance (1). Patients requiring a cardiotocograph (CTG) more often than once weekly are frequently hospitalized for closer surveillance. This is costly, and involves considerable patient inconvenience and anxiety. In 1986. a telephone-linked system of fetal heart rate monitoring from the patient's home was developed (2). Field testing was performed in 5 major British centres. and the Domiciliary Fetal Monitoring (D.F.M.) system then became commercially available (3). In February 1987, the Hull Maternity Hospital began employing D.F.M. for antenatal fetal surveillance, and was the first district hospital to purchase this equipment. The aims of the study were to assess: 1. The percentage of abnormal recordings in the first 100 patients who underwent domiciliary monitoring. 2. The obstetric and neonatal outcome of the study group, compared with the outcome of all patients booked for hospital confinement. 3. The changes in hospital admission rates and midwifery workload which occurred following the introduction of the new system. 4. Midwife and patient opinion of the DFM System. PATIENTS AND METHODS
The Hull Maternity Hospital conducts 4,400 confinements per annum. It serves a mixed urban and rural population. Peripheral antenatal clinics are also conducted in 2 coastal centres, located 28 and 35 kilometres from the central hospital. Patients were recommended for Domiciliary Fetal Monitoring by any of the 5 obstetric consultants, 1 senior registrar and 3 registrars. Patients were selected on the basis of suspected fetal compromise, in the absence of other complications of pregnancy such as proteinuric hypertension, if the degree of risk was not deemed sufficient to warrant immediate obstetric intervention. Monitoring was performed daily, twice weekly, or on an occasional basis, (the latter most commonly for patients reporting less than 10 fetal movements on a daily Cardiff Kick Chart). Frequency of monitoring was determined on the basis of degree of clinical concern. The Huntleigh Domiciliary Fetal Monitoring System was used (Huntleigh Technology PLC, Healthcare Division, Cardiff, Wales) (2). Eight portable ultrasound fetal heart rate (FHR) monitors were linked via teiephone to a computer receiver, which was housed in the Delivery Suik of the Hull Maternity Hospital. Hospital inpatients learned self-monitoring prior to their discharge. Outpatients were visited by a Community Midwife, who made the recording, or in-
structed the patient if long-term monitoring was required. Even in the latter case, midwives generally transported the remote monitors to and from patient's homes, owing to their limited supply. But patients living in the same district often snared the monitor amongst themselves, and monitors for the coastal villages were kept in the local health centre. Fetal movements were noted by the patient using a hand-held event marker during the recording. The compressed signal was transmitted via an acoustic coupler over the telephone line within 45 seconds. The FHR tracing was sent to a dedicated telephone in the labour ward, to avoid interference from the hospital switchboard. The patient's obstetric details and indication for fetal monitoring were recorded. The fetal heart tracing was assessed by the duty obstetric registrar, in regard to baseline rate, variability, reactivity to fetal movements, or fetal heart rate declarations. A recording in which less than 40% of the FHR signal was actually received by the central computer was considered inadequate for reporting. The receiving clinician then adopted one of 3 management plans: 'Repeat as initially directed' (trace satisfactory), 'Repeat later same day' (because tracing technically inadequate), or, 'Patient to attend Labour Ward' (trace suggests fetal compromise). A copy of the domiciliary CTG was filed in the patient's case notes, and a second copy was held in a research file for the purpose of this study (Figure 1).
----- HUNILEIP DIR ----htient nane Rcftllence no Rcerdedcd at Recorded 4 Gestation age Parity Indication -
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letion ; see 2t: iW8 Lt : 1430 i 18/3/88 Qpyright (C) university of wlrs college of mdicine 1986 876
Figure 1. Example of domicitiary fetal monitoring record.
Assessment of the D.F.M. system The pregnancies of the first 100 consecutive patients who underwent Domiciliary Fetal Monitoring in Hull between March, 1987 and June, I988 were
N.Z. JOURNALOF OBSTETRICS AND GYNAECOL~GY
studied. The total number, and result, of recordings for each patient was noted. Obstetric and neonatal outcome for each pregnancy was determined from the case notes, and compared with outcomes for all patients booked for hospital confinement at the Hull Maternity Hospital in 1987. The number and duration of hospital admissions for fetal surveillance in 3 categories (suspected growth retardation, reduced fetal movement and poor previous obstetric history) were studied, for the 2 &month periods before and after the introduction of DFM. Consultant policy regarding diagnosis and management of these conditions was not formally altered before or during the study period. Conditions for which hospital admission was considered obiigatory, such as antepartum haemorrhage or proteinuric hypertension, were excluded from analysis. The 22 community midwives involved in the DFM system were surveyed regarding its impact upon their workload, and their opinion of its value. Time spent in providing the DFM service, whether by recording the traces, or by delivering and retrieving the monitors, was determined from the midwives' logbook, which was recorded prospectively during the first 4 months of the study, and kept in each peripheral monitor case. Technical problems in recording and transmission of F.H.R. tracings were determined from the log-books, and from the research file of all DFM recordings. A postal survey of patient's views on the D.F.M. System was performed 6-12 weeks after delivery.
patients were primigravidas and 64 were multiparas. Seventy-four per cent were telephone subscribers. The gestation at which DFM commenced varied from 28 to 41 weeks. The number of recordings made per patient varied from 1 to 41 (mean value of 5.22 recordings). Four patterns of DFM usage reflected the varying levels of clinical concern: Daily long-term (54% of traces), Daily short-term (200ro), Twice weekly (17%) and Once only (9'70)(table 1). Patients undergoing long-term daily monitoring because of poor previous obstetric history (n=7) had all experienced a stillbirth or early neonatal death; many had undergone prolonged hospitalization in previous pregnancies. Thirty-nine of the patients used the system because of reduced ( c lO/day) fetal movements; most of them would normally have attended t h e l a b o u r ward at night f o r cardiotocography . The majority of traces (82.7%) were technically and clinically satisfactory (figure 2). Technical problems, such as failed batteries in the portable
RORML OH C l G
The 100 patients who underwent fetal monitoring were aged 15-41 years (mean 24.5 years). Thirty-six
Figure 2. Results of 522 domiciliary fetal monitoring traces.
Table 1. Patterns of Use of Domiciliary Fetal Monitoring Indications for DFM Number Mean gestation Mean No. Total No. of pts at start of DFM/pt DFM DFM Daily long-term Prev Ob Hx 5 34.2 27.2 136 (>3 weeks) IUGR 5 34.8 20.6 105 Reduced FM 2 36.0 22 44 12 285 Daily, short-term IUGR 12 38.6 4.2 51 Reduced FM 14 38.5 3 41 Hypertension 3 37.6 3.3 10 Postdates 1 41 4 4 30 106 Twice-weekly Prev Ob Hx 2 35.5 4 8 IUGR 9 34.4 1.3 66 Reduced FM 3 38.6 4.3 13 14 87 Once only Prev Ob Hx 3 39 1 3 IUGR 16 37.2 1 16 Reduced FM 20 38.2 1 20 Hypertension 2 38 1 2 Postdates 3 41 1 3 44 44 Total 100 522 Prev Ob Hx = previous obstetric history; FM = fetal movement; IUGR = suspected intrauterine growth retardation; DFM = domiciliary fetal monitoring Frequency of DFM
KATEH. MOOREAND RICHARDSILL
Tabk 2. Obstetric and Neonatal Outcome
induced Normal delivery Caesarean section Forceps Birthweight < 10th per centile Stillbirths Neonatal deaths Perinatal mortality rate
Abnormal DFM N = 9
N = 91
N = 100
9 (10%) 5 (55Vo) 3 (33%) I (11%)
29 (32%) 82 (9OVo) 8 ( 9Vo)
1 ( 1%)
5 (55%) 0
39 (43%) 0 2 (2.2%) 2 (2.2%)
Allbooked patients N = 4,393 (mi) 11.7vo 86.3qo 10.2vo 3.5%
20 0.46% 42 O.%%
DFM = domiciliary monitoring
monitors, or malfunction of the fetal movements marker, occurred in 8% of recordings: a satisfactory test was repeated later that day in the patient's home. The signal pick-up rate was less than 40% (and therefore not suitable for reporting) in 3.2% of domicilary recordings. This most commonly occurred because of poor contact, due to fetal position or movement. A satisfactory result was obtained at home later the same day. Thirty-one tracings (5.9%) suggested fetal compromise; these patients attended labour ward for full assessment, which revealed a satisfactory pregnancy in 22 patients. They returned home, to continue domicilary monitoring. In the remaining 9 patients, fetal compromise was also suspected on the labour ward cardiotocograph. All were hospitalized: 3 patients were delivered within 12 hours and all were delivered within 7 days. The operative delivery rate for this group was trebled or more, with respect to the remaining 91 study patients (table 2). Obstetric and neonatal outcome for study group Of the 100 study patients, 38 underwent induction of labour, a rate 3.2 times greater than for all hospital confinements in the same year (11.7Vo). Eleven patients underwent Caesarean section, (6 elective and 5 emergency procedures) which was similar to the Caesarean section rate for this hospital in the same year (10.2%). The forceps delivery rate was also similar (table 2). Forty-four infants had birthweights below the tenth percentile for gestational age on GairdnerPearson normogram, after correction for sex of the infant. Of these, 17 infants were markedly small for dates (< 3rd percentile birth-weight). Two neonatal deaths occurred, at 56 hours after delivery, (septicaemia), and 5 days after delivery (nephrogenic diabetes insipidus). Hospital admission for fetal surveillance before and after DFM The number of patients admitted because of suspected growth retardation, reduced fetal movements or poor previous obstetric history declin-
ed by 29%, over the 2 &month periods before and after DFM was introduced. The time spent in hospital was reduced by 53% (table 3). The number of admissions for other antenatal conditions (for which DFM was inappropriate) changed little during the 2 study periods (856 and 827 respectively, a reduction of 3.4%). Tabk 3. Comparison of Admissions for Fetal S~~elllaace. Before and After introduction of DFM Svstcm
Indication for admission Suspected IUGR Reduced fetal movements Previous obstetric historv Total admitted
Before DFM After DFM Aug. 1986-Jan.Aug. 1987-Jan. 1987 1988 No. of Days in No. of Days in patients hospital patients hospital