196 Thornton et al., Heart rate post-term

Original articles

J. Perinat. Med.10 (1982) 196

Antepartum fetal heart rate testing and the post-term gestation

Yvonne S. Thornton, Sze-Ya Yeh, Roy H. Petrie

From the Sloane Hospital for Women and the Section of Perinatal Obstetricsof the Division of Perinatal Medicine of the College of Physicians and Surgeons,Columbia-Presbyterian Medical Center, New York, New York

l Introduction

With the advent of continuous fetal heart ratemonitoring, the obstetrician has been better ableto assess the Status of fetal well-being in normaläs well äs high risk pregnancies. Antepartum fetalheart rate testing (AFHRT) was first introducedby HAMMACHER [5,6]. Subsequently, the test hasbeen refined and popularized in the United Statesby several groups [13, 14].It is well-known that the post-term fetus is subjectto increased perinatal morbidity and mortalityfrom fetal dysmaturity, fetal distress, meconiumaspiration, congenital anomalies and macrosomia[3, 8, 9, 18]. Recent literature on AFHRT hasdemonstrated that the largest single high risk in-dication for the performance of an AFHRT is thatof the post-term gestation [10, 15]. Because thepost-term gestation comprises the largest popula-tion in these previous studies, we have attemptedto isolate and examine this group of patients atincreased risk for placental insufficiency. The pur-pose of this study is to evaluate the experience atthe Columbia-Presbyterian Medical Center withAFHRT in the management of the post-term gesta-tion.

2 Patients and procedures

The study group consisted of both ward and pri-vate patients from the Sloane Hospital for Womenat the Columbia-Presbyterian >Medical Center.These patients underwent AFHRT because ofsuspected post-term gestation. From 1974 through

Curriculum vitae

YVONNE S. THORNTONwas born in 1947 in NewYork, New York. She re-ceived her medical degreein 1973 from the Collegeof Physicians and Surgeonsof Columbia University inNew York. She completedher residency in Obstetricsand Gynecology at TheRoosevelt Hospital in NewYork. She has done inde-pendent research at TheRockefeller University inNew York in hematology and ehdocrinology. In 1979, shecompleted a two-year fellowship in Maternal-Foetal Medi-cine at the Babies Hospital and The Sloane Hospital forWomen, Columbia-Presbyterian Medical Center, NewYork. Her main research interests are antepartum fetalmonitoring, fetal acid-base physiology and fetal pharma-cology.

1977, the contraction stress test was used alone.From 1977 through 1978 both the contractionstress test and the non-stress test were employedäs methods for antepartum fetal surveillance. Onlythose low-risk patients whose pregnancies hadprogressed beyond 42 weeks from the last men-strual period were included in the study. The con-traction stress test (CST) technique was performedäs described by RAY [13], i.e., the observation ofthe fetal heart rate for late decelerations duringthree spontaneous or oxytocin induced contrac-tions occurring in a ten minute interval. The non-stress test (NST) was performed äs outlined by

0300-5577/82/0010-0196$02.00© by Walter de Gruyter & Co. - Berlin - New York

Thornton et al., Heart rate post-term 197

NOCHIMSON [10], i.e. the occurrence of at leastfour fetal movements in a 20 minute interval, eachof which is associated with a fetal heart accelera-tion which lasts fifteen seconds with a maximumamplitude of at least fifteen beats per minute. Alltests were performed by perinatal nurse specialistsand interpreted by the same investigator (R.H.P.).Patients were entered in the AFHRT protocol ona voluntary basis, therefore some post-term pa-tients were electively excluded from the protocoland were placed in the prospective control group(1974-1979). The neonate was evaluated forpostmaturity by neonatologists and by the DUBO-WITZ classification [2]. There were two controlgroups. The retrospective control group (Controlgroup number 1) included those post-term patientswho delivered in the five years preceding the studyperiod (1969-1974). This control group did nothave the benefit of AFHRT. The prospectivecontrol group (Control group number 2) includedthose post-term patients who did not receiveAFHRT during Hie study period (1974-1979).The prospective study group consisted of thosepost-term patients who received AFHRT between1974-1979.Management of the post-term patients was äsfollows: 1) Service patients at 41+ weeks of gesta-tion, äs derived from the last menstrual period orsecond trimester ultrasonography, were referred tothe High Risk Clinic the following week. Theprivate patients who were post-term were followedby their personal physicians, 2) in the High RiskClinic when the patient was 42+ weeks, 24-hoururinary estriol levels were obtained weekly and iffeasible, amnioscopy was performed. Those pa-tients who chose to be in the study underwentAFHRT on a weekly basis, 3) the preceding man-agement was generally followed on the privateService, except when amniocentesis was performedby some practitioners in order to ascertain thepresence or absence of meconium in a patient withan unfavorable cervix.Management protocol of the patients receivingAFHRT included the following: 1) a negative testor a reactive test was repeated within one week,unless urinary estriol levels feil significantly, inwhich case the AFHRT was repeated more oftenor the patient was induced, 2) a suspicious or non-

reactive test was repeated within 24 hours, 3) apatient with a suspicious or non-reactive test wasfurther evaluated for fetal well-being, pulmonarymaturity, cervical Status with consideration fortermination of pregnancy, 4) patients with a favor-able BISHOP's score were induced, 5) the patientwith a positive contraction stress test was exam-ined and those with a favorable score underwentinduction and the patients with an unfavorableBISHOP's score underwent caesarean section.Outcome äs judged by APGAR score, meconiumstaining, mode of delivery and perinatal loss wereevaluated. The determination of meconium forclinical evaluation was made at the time of admis-sion with amnioscopy or at the time of ruptureof membranes. The test of statistical significancewas the ordered Chi-square test with YATES' cor-rection when applicable.

3 Results

In the interval 1969—1974, there was an annualaverage of 3,260 deliveries weighing greater than2500 grams of which 445 were post-term gesta-tion (2.7 percent). This group of patients made upcontrol group number 1. In the interval 1974—1979, there was an annual average of 2,545deliveries of greater than 2500 grams of which 404were post-term gestation (3.2 percent). Of the 404patients in the 1974-1979 interval, 314 under-went AFHRT for post-term gestation. This groupwas the study group. Control group number 2consisted of the 90 post-term patients in the1974-1979 interval who did not receive AFHRT.The private-ward ratio in the AFHRT group was40/60, which also was the ratio for total private/ward patients who delivered in the Sloane Hospitalfor Women. AFHRT was performed 602 times on314 patients. There were 300 CST alone, 180 NSTalone and 61 NST with CST.The perinatal outcome äs it relates to 5 minuteAPGAR scores of 7 or greater, APGAR scores ofless than 7, stillbirths and neonatal deaths aregiven for both control groups and the study groupin Tab. I. Statistical analysis demonstrated thatthere was a significant difference in perinatalmortality between the study group and the controlgroup number l (p < 0.01). There was also a

J.Perinat.Med. 10(1982)

198 Thornton et al., Heart rate post-term

Tab. I. Perinatal outcome.

Control #1Control #2Study group

APGAR score> 7 (5 min)

387 (87.0%)84 (93.3%)

308 (98.1%)

APGAR score< 7 (5 min)

39 (8.8%)4 (4.4%)4 (1.3%)

Stillbirths

910

(2.0%)(1.1%)

— . tNeonatal deaths

10 (2.2%)1 (1.1%)2* (0.6%)

Total

44590

314

a) Complication of amniocentesis b) Extensive congenital anomalies

highly significant difference (p <0.01) comparingthe perinatal morbidity between control groupnumber l and the study group. When the com-parison was performed comparing the study groupand control group number 2, there was a signifi-cant difference in perinatal morbidity (p < 0.05):however, there was no statistical difference be-tween these two groups in perinatal mortality.Statistical analysis of control group number l andcontrol group number 2 revealed no statisticaldifferences in either perinatal mortality or perina-tal morbidity.Of the 314 study patients, 303 were allowed tolabor. Sixtyseven of these 314 patients had an ab-normal AFHRT. During the era prior to the use ofthe NST, 45 of these 67 patients had an abnormalCST: 3 patients with a positive test underwentcaesarean section because of an uninducible cervixand 42 patients had a suspicious test of which 26had a vaginal delivery (13 had spontaneous onsetof labor and 13 were induced) and 16 underwentcaesarean section for the following indications: 4for cephalopelvic disproportion, 9 for fetal distress,l developed severe pre-eclampsia with an unfavor-able cervix and 2 had thick meconium with lowBISHOP's scores. Following the adoption of theNST, there were 22 patients with a non-reactiveNST and a suspicious CST: 16 delivered vaginally(l l had spontaneous onset of labor and 5 wereinduced) and 6 underwent caesarean section forthe following indications: 3 for cephalopelvic dis-proportion, 2 for fetal distress and l had thickmeconium with a low BISHOP's score. Of the 67patients who had an abnormal AFHRT, 42 percenthad meconium. Meconium was present in only21.5 percent of the patients with normal AFHRT.This difference was statistically significant(p < 0.001). The complete data are given inTab. II.

Of the 314 study patients, 95 were delivered bycaesarean section. When the group of patientswith abnormal AFHRT were compared to thegroup with normal AFHRT, there was no statis-tically significant difference in the percent ofpatients delivered by caesarean section in eachgroup.Using the DUBOWITZ score äs a marker for thepost-term gestation, abnormal and normal AFHRTresults were compared. Of those babies with anormal AFHRT, 95 of 247 infants were classifiedäs post-term. Of those babies with abnormalAFHRT, 37 of 67 were classified äs post-term(p < 0.05). There were three instances of positiveCST. All underwent caesarean section, äs previ-ously mentioned and all three had the clinicalfindings and DUBOWITZ scores indicating post-term/postmäturity syndrome.The intrapartum fetal heart rate tracings of the303 patients who were allowed to labor werereviewed for the presence or absence of moderateor severe variable decelerations during labor. Thepresence of variable decelerations during the firststage of labor was compared to the abnormal andnormal AFHRT tracings. It was found that 57 of247 patients (23.1 percent) with normal AFHRThad variable decelerations during labor. Thirty-sixof 56 patients (64.3 percent) with abnormalAFHRT had variable decelerations during labor.

Tab. II. Meconium possage (314 patients).

Normal APFHRTAbnormal APFHRT

Nomeco-nium

19439

Withmeco·^nium

53 (21.5%)28 (41.8%)

24767

X2 = 11.38 p < 0.001

J. Perinat. Med. 10 (1982)

Thornton et al., Heart rate post-term 199

This difference was highly significant (p < 0.001).Approximately one-third to onehalf of thepatients in control group number l received intra-partum electronic fetal heart rate monitoring,most in the latter years of the five year period(1969-1974). In the prospective control groupnumber 2, consisting of 90 patients, 83 wereallowed to labor. Eighty-two had intrapartumelectronic fetal heart rate monitoring; the still-birth was not monitored. Of these 82 patients, 27had evidence of moderate to severe variabledecelerations (32.9 percent).Inasmuch äs the last menstrual period is the majorsource from which the estimated date of confine-ment is derived, the patients in the study groupwere divided into nine categories, according to thelength of gestation. The shortest gestation was 42to 43 weeks and the longest gestation was 48 to49 weeks. The groups were further categorizedinto the trimester when they were first seen andevaluated. The findings indicated that 122 (38.9percent) were first seen in the first trimester, 127(40.4 percent) were first seen in the second tri-mester and 65 (20.7 percent) were first seen in thethird trimester. Three patients whose pregnancieshad progressed to 48-49 weeks, by their lastmenstrual period, were seen initially at 40 weeksof gestation and were followed with AFHRT for8—9 weeks without any perinatal morbidity ormortality. The physical findings and DUBOWITZscores indicated that these three infants were post-mature. The data also showed that there was nocorrelation between an abnormal AFHRT and theincrease in length of gestation.There were two neonatal deaths in the studygröup. The first was attributed to an inadvertentlaceration o the umbilical cord during amnio-centesis. This patient had three suspicious contrac-tion stress tests. The second death was due to alarge diaphragmatic hernia of BOCHDALEK and bi-lateral pulmonary hypoplasia. This patient had areactive non-stress test and had no evidence ofvariable decelerations or other signs* of fetaldistress during labor.

4 Discussion

Perinatal loss in pregnancies with evidence of pla-cental insufficiency, äs seen in the post-term gesta-

tion, is estimated in some studies to be three timesnormal [16, 18]. In this study, the significant in-crease in the occurrence of moderate to severevariable decelerations could be attributed to thedecrease in the amount of amniotic fluid äs welläs the decrease in the fluid content of WH AR-TON 's jelly in the cord. These changes, which areassociated with the prolonged pregnancy, mayexplain the increase of umbilical cord compressionin these patients.An earlier report [7] describes the lack of correla-tion among post-maturity, abnormal AFHRT andmeconium. Contrary to this study, our results havedemonstrated that there is a definite correlationamong post-maturity, abnormal AFHRT and thepresence of meconium in the post-term gestation.In this ten-year study, the two control groups weredesigned to eliminate any differences in the perina-tal morbidity and mortality based solely on thetechnical improvement of neonatal resuscitationand neonatal intensive care. As seen in the results,there was still a significant difference in perinatalmorbidity when the study group was comparedwith its internal control (Control group num-ber 2).FREEMAN [4] reported a high false positive ratefor the contraction stress test, approaching 25percent. Other studies have placed the false posi-tive CST rateas high äs 45 percent [12]. Fewinvestigators have examined the false positive rateof the non-stress test, i.e., a non-reactive non-stresstest with a subsequent negative contraction stresstest. This study, agreeing with those publishedreports [17], demonstrated a false positive rate forthe non-stress test of 27.4 percent with a falsenegative rate of 0.6 percent. Despite its high falsepositive rate, the non-stress test in conjunctionwith the contraction stress test was a reliableindicator for fetal compromise in the post-termgestation.In the study group, when the patients were notinducible, confidence in AFHRT enabled thesepatients to continue their pregnancies up to 48and 49 weeks without any increase in perinatalmorbidity or mortality.The relationship of abnormal AFHRT findings(variable decelerations) and the presence ofvariable decelerations on the fetal heart rate

J. Perinat. Med. 10 (1982)

200 Thornton et al., Heart rate post-term

tracing during labor may be of some prognosticvalue for the potential of cord problems. Thesefmdings support the work of BRUCE [1] andO'LEARY [11], which demonstrated the impor-tance of AFHRT changes in caring for the post-term fetus during labor.These data clearly demonstrate that AFHRT is areliable surveillance System for the post-termgestation and that it has demonstrated a signifi-cant lowering of perinatal morbidity and perinatalmortality in the study group.Obstetricians are all too familiär with the patientwho presents late in her pregnancy with an un-certain last menstrual period and is two weeksbeyond her estimated date of confmement. This

dilemma poses a multitude of problems whichmay have far-reaching consequences for the fetusand neonate. In the final analysis, one must eithertemporize and await the onset of spontaneouslabor or intervene and terminate the pregnancy forfear of increased perinatal morbidity and mor-tality.With AFHRT, there is a rapid and practical methodfor assessing placental function and fetal well-being, permitting accurate selection of a smallgroup of infants for whom further Prolongation ofintrauterine life would be disastrous. The results ofthis study have shown that AFHRT has a signifi-cant impäct on decreasing perinatal morbidity andmortality associated with the post-term gestation.

Summary

This study has examined the role of antepartum fetalheart rate testing (AFHRT) in the management and out-come of the post-term gestation It spanned a ten yearperiod from 1969 to 1979 and was conducted at theSloane Hospital for Women at the Columbiä-PresbyterianMedical Center in New York.A study group was composed of 314 patients at 42+weeks gestation who were managed with AFHRT. Therewere two control groups. Control group number oneincluded those post-term patients delivered in the fiveyears preceding our study period (1969-1974). Thisgroup did not have the benefit of AFHRT. Control groupnumber two included those post-term patients who didnot receive AFHRT during the study period (1974-1979). In addition to the AFHRT, adjunctive testingincluded 24-hour urinary estriol, ultrasonographic B scan,amnioscopy and amniocentesis, when indicated. Patientswere entered into the AFHRT protocol on a voluntarybasis.Statistical analysis demonstrated a significant differencein perinatal morbidity and mortality between the studygroup and control group number one. There was a sta-tistically significant difference in the perinatal morbiditybetween the study group and control group number two.Patients with abnormal AFHRT had a statistically signifi-cant increase in the incidence of intrapartum variabledecelerations, meconium and the post-term/postmaturitysyndrome. Three patients whose pregnancies had pro-

gressed to 48—49 weeks, by their last menstrual period,were seen initially at 40 weeks gestation and were fol-lowed with AFHRT for 8-9 weeks withoüt any perinatalmorbidity or mortality. The physical findings and theDUBOWITZ scores indicated that these thfee infants werepostmature.There were two neonatal deaths in the study group. Theflrst was attributed to an inadvertent laceration of theumbilical cord during amniocentesis. The second deathwas due to a large diaphragmätic hernia of BOCHDALEKand bilateral pulmonary hypoplasia.This study also demonstrated a false positive rate for thenonstress test of 27.4 percent with a false negative rate of0.6 percent. Despite its high false positive rate, the non-stress test in conjunction with the contraction stress testwas a reliable indicatof for fetal comprornise in the post-term gestation.Suspected postmaturity continues to be a problem for theclinician. One must either temporize and await the onsetof spontaneous labor or intervene and terminate thepregnancy for fear of increased perinatal morbidity andmortality.With AFHRT, there is an accurate selection of a smallgroup of infants for whom further Prolongation in intrau-terine life could be disastrous. The results of this studyhave shown that AFHRT has a significant iinpact ondecreasing the perinatal morbidity and mortality asso-ciated with the post-term gestation.

Keywords: Antepartum fetal heart rate testing, contraction stress test, non-stress test, perinatal morbidity, perinatalmortality, post-term gestation.

Zusammenfassung

Antepartale fetale Herzfrequenzmessung bei übertragenerSchwangerschaftIn unserer Studie untersuchten wir die Relevanz der ante-partalen Herzfrequenzmessung für die Schwangerschafts-überwachung und -beendigung bei Übertragung. Die Un-

tersuchungen umfassen einen Zeitraum von 10 Jahrenzwischen 1969 und 1979 und wurden am Sloane Hospitalfor Women am Columbiä-Presbyterian Medical Center inNew York durchgeführt.

J. Perinat. Med. 10 (1982)

Thornton et al., Heart rate post-term 201

In der Untersuchungsgruppe waren 314 Patientinnen abder 42. SSW., bei denen die antepartale fetale Herzfre-quenzmessung durchgeführt wurde. Daneben gab es zweiKontroilgruppen: Kontrollgruppe l umfaßte jene Patien-tinnen, die nach übertragener Schwangerschaft zwischen1969 und 1974 entbunden haben; in der Kontrollgruppe2 waren Patientinnen aus dem Zeitraum 1974-79, bei de-nen ebenfalls keine Herzfrequenzmessung erfolgte. Beientsprechender Indikation wurden in der Untersuchungs-gruppe zusätzlich zur Herzfrequenzmessung weitere Testsdurchgeführt wie z.B. Östriolausscheidung im 24-h-Urin,Ultraschallmessungen, Amnioskopie und Amniozentese.Alle Patientinnen unterzogen sich unserem Testprogrammauf freiwilliger Basis.Die statistische Analyse ergab einen signifikanten Unter-schied hinsichtlich der perinatalen Morbidität und Mor-talität zwischen der Untersuchungsgruppe und der Kon-trollgruppe l, während der Unterschied zwischen der Un-tersuchungsgruppe und der Kontrollgruppe 2 nur hin-sichtlich der perinatalen Morbidität statistisch signifikantwar. Ergab die antepartale Herzfrequenzmessung patho-logische Befunde, so traten intrapartale variable Dezelera-tionen, mekoniumhaltiges Fruchtwasser und Übertra-gungssyndrome signifikant häufiger auf. Bei 3 Patientin-nen, die laut letzter Regel in der 48.-49. Woche warenund seit der 40. SSW. überwacht wurden, gab es in derperinatalen Phase keine Komplikationen. Nach der kör-Schlüsselwörter: Antepartale fetale Herzfrequenzmessung, Kontraktionsbelastungstest, Non-stress-Test, perinatale Mor-

bidität, perinatale Mortalität, übertragene Schwangerschaft.

perlichen Untersuchung und dem DUBOWITZ-Scorewurden diese Kinder als postmatur eingestuft.In der Untersuchungsgruppe traten 2 neonatale Todes-fälle auf. In einem Fall war es während einer Amniozen-tese zur Verletzung der Nabelschnur gekommen; daszweite tote Kind hatte große Bochdalek'sche Hernien undeine bilaterale Pulmonalhypoplasie.Die Studie ergab weiter, daß der Test ohne Belastung in27,4% falsch positiv war gegenüber einer falsch negativenRate von 0,6%. Trotz dieser hohen Rate an falsch positi-ven Ergebnissen war der Test ohne Belastung in Zusam-menhang mit Kontraktionsauslösungen ein verläßlicherIndikator für die fetale Gefährdung bei Übertragung.Der Verdacht auf Übertragung stellt weiterhin ein Pro-blem für den Kliniker dar. Es gilt einerseits den Beginnspontaner Wehen abzuwarten und andererseits zum rich-tigen Zeitpunkt zu intervenieren und die Schwangerschaftzu beenden, um so eine erhöhte perinatale Morbidität undMortalität abzuwenden.Mit der antepartalen fetalen Herzfrequenzmessung ist esmöglich, die kleine Gruppe von Kindern zu selektionieren,für die eine weitere Verlängerung des intrauterinen Le-bens verhängnisvoll sein könnte. Unsere Ergebnisse zei-gen, daß diese Methode einen bedeutsamen Beitrag zurHerabsetzung der mit Übertragung einhergehenden peri-natalen Risiken leistet.

Resume

Contröle du rythme cardiaque foetal pendant la grossesseet grossesses prolongeesDans ce travail les auteurs ont etudie le role du controledu rythme cardiaque foetal (RCFC) pur la prise en Chargeet le devenir des grossesses prolongees. L'etude porte surune decennie, de 1969 a 1979, et a ete effectuee audepartement feminin Sloane du centre medical Columbia-Presbyterian de New-York.314 patientes enceintes de 42 semaines ou plus et surveill-ees par RCFC ont constitue le groupe etudie. Deuxgroupes temoins ont ete 6tablis. Dans le premier sontincluses les patientes ayant äccouche apres terme pendantles 5 annees precedant le debut de l'etude (1969-1974).Ces patientes n'ont pas beneficie du RCFC. Le deuxiemegroupe temoin comprend les patientes äyant äccoucheapres terme mais sans avoir eu de RCFC pendant laPeriode de l'etude (1974-1979). En plus du RCFC,d'autres examens ont ete effectues lorsqu'ils etaientindiques, dosage de l'estriol urinaire des 24 heures,echographie, amnioscopie, et amniocentese. Le volon-tariat etait a la base du protocole RCFC pour les patientesincluses.L'analyse statistique met en evidence une differencedignificative pour la morbidite et la mortalite perinatalesentre le groupe etudie et le groupe n° 1. La differenceest statistiquement significative sur la morbidite perinataleentre le groupe etudie et le groupe n° 2. Les patientespresentant un RCFC anormal ont une augmentation

syndrome post-terme/postmaturite. Trois patientes dontles grossesses se sont poursuivies jusqu'a 48-49 semaines,comptees a partir des dernieres regles, ont ete vues pourla premiere fois ä 40 semaines et ont ete suivies avecRCFC pendant 8 a 9 semaines sans morbidite ou mortaliteperinatales. Les donnees cliniques et les scores de DUBO-WITZ confirment que ces trois enfants etaient post-matures.Deux morts neonatales ont ete observees dans le groupeetudie. La premiere a ete imputee ä une lesion malen-contreuse du cordon ombilical lors de Famniocentese. Laseconde etait en rapport avec une enorme herniediaphragmatique de BOCHDALEK et avec une hypoplasiepulmonaire bilaterale.Cette etude a aussi mis en evidence 27,4 pour-cent defaux positifs du nonstress test et 0,6 pour-cent de fauxnegatifs. Malgre la forte frequence de faux positifs, lenonstress test couple au test au syntocinon represente unindicateur fiable de l'etat foetal au cours des grossessesprolongees. La suspicion de postmaturite reste unProbleme pour les cliniciens. Les uns temporisent etattendent le declenchement spontane du travaü, les autressont actifs et interrompent la grossesse par crainted'augmenter la morbidite et la mortalite p6rinatales.Le RCFC permet la selection reelle d'un petit grouped'enfants pour lesquels la Prolongation de la vie intra-uterine pourrait etre desastreuse. Les resultats de cetteetude ont montre que le RCFC a un impact significatif surla diminution de la morbidite et de la mortalite perinatalesqui sont le lot des grossesse prolongees.

significative de la frequence des decelerations variables encours de travaü, de la presence de meconium et duMots-cles: Etude du rythme cardiaque foetal pendant la grossesse, grossesses prolongees, morbidite perinatale, mortalite

perinatale, non-stress test, test au syntocinon.

J. Perinat. Med. 10(1982)

202 Thornton et al. Heart rate post-term

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Received February 11, 1982 Accepted March 15, 1982.

Yvonne S. Thornton, M. D.The New York Hospital - Cornell Medical CenterDepartment of Obstetrics-Gynecology525 East 68th StreetNew York, New York 10021

J. Perinat. Med. 10 (1982)