CITATION: Reinhardt, G., Odendaal, H.J. & Kotze, T.J.v.W. 1987. Spontaneous prolonged contractions during antenatal fetal heart rate monitoring . S Afr Med J, 71(1):17-19.The original publication is available at http://www.samj.org.zaENGLISH ABSTRACT: Uterine contractions of more than 2 minutes' duration occurred spontaneously in 1.4% of 6399 antenatal fetal heart rate (FHR) recordings. All recordings were made in the Department of Obstetrics and Gynecology at Tygerberg Hospital. The patients with spontaneous prolonged contractions (SPC) were compared with a randomly selected control group. Patients who had an SPC during antenatal FHR recording were not at a higher risk of abruptio placentae, preterm labour or unexpected intra-uterine death. Of the infants born to the mothers in the study group, 65.5% were male. There were more primigravidas in the study group, which may have been responsible for the longer duration of the second stage of labour in this group. When primigravidas only were examined no difference between the two groups could be found except for a larger placental mass in the study group. It is uncertain why primigravidas were more likely to develop SPCs as observed during antenatal FHR monitoring.Publisher’s versio

Kotze, T. J. v. W.

Odendaal, H. J.

Rienhardt, G.

Stellenbosch University SUNScholar Repository

SAMJ VOLUME 71 10 JANUARY 1987 17Spontaneous prolonged contractions duringantenatal fetal heart rate monitoringG. RIENHARDT, H. J. ODENDAAL, T. J. v. W. KOTZE•SummaryUterine contractions of more than 2 minutes' durationoccurred spontaneously in 1,4% of 6399 antenatalfetal heart rate (FHR) recordings. All recordings weremade in the Department of Obstetrics and Gynaeco-logy at Tygerberg Hospital. The patients with spon-taneous prolonged contractions (SPC) were com-pared with a randomly selected control group.Patients who had an SPC during antenatal FHRrecording were not at a higher risk of abruptioplacentae, preterm labour or unexpected intra-uterinedeath. Of the infants born to the mothers in the studygroup, 65,5% were male. There were more primigra-vidas in the study group, which may have beenresponsible for the longer duration of the secondstage of labour in this group. When primigravidasonly were examined no difference between the twogroups could be found except for a larger placentalmass in the study group. It is uncertain why primi-gravidas were more likely to develop SPCs asobserved during antenatal FHR monitoring.S Atr Med Jl987; 71: 17-19-Antenatal fetal heart rate (FHR) monitoring to assess fetalwell-being is frequently carried out in the Department ofObstetrics and Gynaecology at Tygerberg Hospital. Duringsome of these recordings spontaneous prolonged contractions(SPCs) of the uterus (Fig. 1) were occasionally observed.Although there are a number of publications 1,2 on oxytocin200180~~ f~, '\160." ,.rrv..r.... if~ \~~\/"'r--..-/.... •140>/ .'" ,_'~:"120 ..~'00Ba60Paper speed 3cm/minFig. 1. The spontaneous prolonged contraction is clearly demon-strated.Department of Obstetrics and Gynaecology, University ofStellenbosch and Tygerberg Hospital, and Institute forBiostatistics of the South Mrican Medical Research Coun-cil, Parowvallei, CPG. RIENHARDT, Medical ScudentH. J. ODENDAAL, F.CO.G. CS.A·l, F.R..CO.G., M.D.T. J. v. W. KOTZE, DSCoverstimulation or excessive uterine contractions after nipplestimulation, SPCs have not yet been reported. As abruptioplacentae is a major cause of intra-uterine death in this unitand since severe abruptio placentae is characterised by abnor-mal uterine activity,3 the question arose whether patients withSPCs are at higher risk of developing abruptio placentae. Asdeceleration of the FHR sometimes occurs during SPCs, wealso wondered whether these patients are at increased risk ofunexpected intra-uterine death. Thirdly, it was postulated thatpatients with these contractions could be at greater risk ofpreterm labour. With these three questions in mind a retro-spective study was performed.Patients and methodsAll antenatal FHR recordings in this department are carefullyfiled in chronological order. For this study the 6399 recordingsobtained in 1983 were reviewed and a study group and a controlgroup of patients were selected. The study group consisted ofpatients with SPCs (> 2 minutes). The recording immediatelyfollowing that of a patient in the study group was selected forinclusion in the control group providing SPCs were absent. If ithad to be excluded for some reason the next recording wasexamined. No patient in either group had had any nipple stimula-tion before the test and none had received oxytocin.All recordings were made with a Hewlett-Packard 8030A cardio-tocograph. The ultrasound transducer was used to record theFHR and an external tocotransducer to measure the uterinecontractions. All the necessary precautions to prevent or excludematernal supine hypotension were always taken.After antenatal FHR tracings for the study and control groupshad been selected, the two groups of patients were compared withrespect to age, gravidity, duration of pregnancy, duration oflabour, birth weight, placental weight and 5-minute Apgar score.Only vaginal deliveries were considered when the duration oflabour was calculated. All the data were analysed by the Institutefor Biostatistics of the South African Medical Research Council.For continuous measurements the distribution of values wasassessed first and then, if the distribution was approximatelynormal, Student's [-test was used to compare groups. When thedistribution deviated too much from the normal the Kruskal-Wallis or Wilcoxon tests were used. For nominal measurements,such as fetal sex, the chi-square test was used to compare thegroups. When the cell counts were too small, Fisher's exact testwas used. A P value of < 0,05 was accepted as statisticallysignificant. For statistical purposes only the first twin wasconsidered. .ResultsOf the 6399 recordings examined only 89 (1,4%) demonstratedSPCs (Table I). Clinical records for 5 patients in the controlgroup could not be found, so 84 patients in each group werestudied. Of the patients in the study group, 8 (9%) of 89 demon-strated during subsequent recordings, while in 9 cases a repetitionof the SPC was found during the same test. Duration of thecontractions ranged from 2 to 7,6 minutes, with a mean (± SD) of3,2 ± 1,2 minutes. When the groups were compared (Table I) itwas found that the patients in the study group had fewer abortions,and the gestational age at the time of initial FHR recording wassignificantly higher. The gravidity of the study group was lower,18 SAMT DEEL 71 10 JANUARIE 1987TABLE I. COMPARISON OF MATERNAL AND FETAL MEASUREMENTS BETWEEN THE STUDY AND CONTROL GROUPSStudy group Control groupMin. Max. Mean SO Min. Max. Mean SO SignificanceAge (yrs) 15 41 24,9 6,5 15 40 26,1 5,7 NSGravidity 1 8 2,2 1,6 1 9 2,7 1,8 NSAbortions 1 0,1 0,3 2 0,3 0,6 P< 0,05Duration of pregnancyP< 0,01at test (wks) 31 47 39 3,6 29 47 37 3,7Duration of pregnancyNSat delivery (wks) 33 47 40,2 3 33 49 40,3 2,8FHR (lmin) 115 160 138 9 125 180 142 10 P< 0,05Duration of firststage (h) 0,5 19,3 7,2 4,3 19,2 6 3,9 NSDuration of secondstage (min) 2 80 19,9 16 2 64 14,7 11,4 P< 0,05Birth weight (g) 1260 5090 3163 618 1700 4700 3169 563 NSPlacental weight (g) 240 1020 589 142 340 1300 585 156 NS5-min Apgar score 1 10 8,3 1,9 1 10 8,8 1,2 P< 0,05NS ;:: not significant at the 5% level.but the difference was not statistically significant. The basal FHRwas lower during the SPCs than the basal heart rate in the controlgroup. The second stage of labour was longer and the 5-minuteApgar score lower in the study group. Other measurements didnot differ significantly.There were 6 sets of twins, 5 in the study group. There werefewer normal deliveries and more vacuum extractions, forcepsdeliveries and caesarean sections in the study group. These dif-ferences, however, were not statistically significant (Table II).Two patients in the study group but none in the control groupdeveloped abruptio placentae. No difference between the twogroups could be found as regards duration of pregnancy at delivery.In the study group 55 (65,5%) of the infants were males; in thecontrol group there were 42 of each sex.Because the gravidity and number of abortions in the twogroups differed, it was decided to investigate the primigravidasonly. There were 67 primigravidas, 41 in the study group and 26in the control group.No difference between the two groups of primigravidas couldbe found in respect of age, duration of pregnancy at time of thetest, or at delivery, duration of t!:le first and second stages oflabour, and fetal weight (Table Ill). The placentas weighed morein the patients with abnormal contractions.More caesarean sections and forceps deliveries were necessaryin primigravidas with SPCs, but the difference was not significant(Table IV). Statistical significance was also not reached when thepatients were separated into operative and normal deliveries.There were no intra-uterine deaths in either group.TABLE 11. METHOD OF DELIVERY IN THE STUDY AND CONTROL GROUPSVacuum CaesareanNormal extraction section ForcepsNo. % No. % No. % No. % Breech TotalStudy group 45 53,6 8 9,5 23 27,4 7 8,3 84Control group 59 70,2 4 4,8 18 21,4 3 3,6 84Total 104 12 41 10 168Pearson .\ 2 \,ll ;:: 5,422; P> 0,05, when the breech delivery was excluded from the calculations.TABLE Ill. COMPARISON OF PRIMIGRAVIDAS IN THE STUDY AND CONTROL GROUPSStudy group Control groupMin. Max. Mean SO Min. Max.. Mean SO SignificanceAge (yrs) 15 34 21,2 4,6 15 38 21,8 5 NSDuration of pregnancyat test (wks) 31 47 39,6 3,5 32 46 38 4,1 NSDuration of pregnancyat delivery (wks) 35 47 40,3 .3 33 49 41 3,9 NSDuration of firststage (h) 2,3 19,3 8 3,7 2 19,2 7,6 4,7 NSDuration of secondstage (min) 4 60 24,1 15,4 5 43 17,6 11,2 NSBirth weight (g) 1260 4200 3055 614 1700 3940 3010 519 NSPlacental weight (g) 240 1020 600 154 380 720 524 87 P< 0,055-min Apgar score 1 10 8,3 2,1 7 10 8,7 0,9 NSNS = not significant.SAMJ VOLUME 71 10 JANUARY 1987 19Study groupControl groupTotalTABLE IV. METHOD OF DELIVERY IN PRIMIGRAVIDASVacuum Caesarean ForcepsNormal extraction section deliveryNo. % No. % No. % No. % Total20 48,8 3 7,3 16 39,0 2 4,8 4115 57,7 4 15,4 7 26,9 2635 7 23 2 67Pearson x2 \,.11 = 1,852; P> 0,05, when the 2 forceps deliveries were excluded from the calculations.DiscussionIn a study like this the selection of a control group is alwaysdifficult, but as far as we could ascertain the only differencebetween the two groups was the absence or presence of SPCs.Contrary to what had been posrulated at the beginning of thesrudy, SPCs did not indicate a great risk of abruptio placentae.The fact that there were 2 cases of abruptio placentae in thesrudy group and none in the control group could point towardsa risk, but a larger series will be needed to confirm this. Itseems that primigravidas develop prolonged contractions moreeasily at an advanced gestational age.It was hoped to obtain an early warning of preterm labour,but the duration of pregnancy in the two groups did not differ.Patients with SPCs were not at increased risk of intra-uterinedeath.The smaller number of abortions in the srudy group isprobably due to the fact that it contained more primigravidas.As labour is usually longer in primigravidas, it is not difficultto explain why the duration of the first and second stages oflabour was longer in the srudy group. The higher number ofprimigravidas in the study group also explains the largernumber of operative deliveries and the lower 5-minute Apgarscores. No differences were encountered when only primigra-·vidas were examined.The higher incidences of twin pregnancies and births ofmale infants as well as the greater placental mass in the studygroup is difficult to explain. Although boys normally havehigher birth weights than girls,4 placentas of boys are relativelylighter than than those of girls,5 but the exact weight of boys'placentas is still higher. The preponderance of boys ·in thesrudy group therefore explains the higher placental weights inthis group. It has been shown that uterine activity is higher inprimigravidas,6 but it is uncertain whether this finding can beextrapolated to the antenatal period. A previous study at thisunit7 demonstrated that patients with biphasic uterine contrac-tions during labour had a higher incidence of operative deliveryresulting from failure of labour to progress. However, thedifference in the rates of operative deliveries between the twogroups in the present study is not statistically significant and itcan therefore not be stated that prolonged contractions recordedantenatally necessarily reflect what will happen during labour.It seems that primigravidas have more SPCs before labour,but the reasons for this finding are not clear.We wish to thank Dr J. P. van der Westhuyzen, MedicalSuperintendent of Tygerberg Hospital, for permission to publish,the Institute for Biostatistics for the statistical analyses, and thenursing staff of the Department of Obstetrics and Gynaecologyfor performing the tests. The study was supported by the SouthAfrican Medical Research Council.REFERENCES1. Viegas OAC, Arulkumaran S, Gibb DMF, Ramam SS. Nipple stimulationin late pregnancy causing uterine hyperstimulation and profound fetalbradycardia. Br J Obsret GynaecoI1984; 91: 364-366.2. Hill WC, Moenning RK, Kau M, Kiumiller JL Characteristics of uterineactivity during breasl stimulation Stress lest. Obs£e' Gynecol 1984; 64:489-492.3. Burchell HI. Odendaal HI. de Wet Jr, Badenhorsr PN. Uterine contractionpanems in abruptio placentae. S Afr MedJ 1985; 67: 48-50.4. Hynen FE, Leitch L The Physiology of Human Pregnancy. 2nd ed. London:Blackwell Scientific Publicalions, 1971.5. McKeown T, Record RG. The influence of placental size of fetal growthaccording to sex and order of binh. J Endocrinol1953; 10: 73-81.6. Arulkumaran S, Gibb DMF, Lunn KC, Heng SH, Ramam SS. The effectsof parity on uterine activity in labour. Br J Obs£e' Gynaecol 1984; 91:843-848.7. Van dee Westhuizen A. Coupling of uterine contractions during labour.Proceedings of the 22nd Congress of the South African Society of Obstetri-cians and Gynaecologists, Port Elizabeth, 9-13 April 1984.

Spontaneous prolonged contractions during antenatal fetal heart rate monitoring

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Spontaneous prolonged contractions during antenatal fetal heart rate monitoring

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