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Fetal Outcome Of Induction Of Labour
Fetal Outcome of Induced Labour Dr. Ganesh Dangal Place of Study: Maternity hospital, Thapathali, Kathmandu, Nepal. Address for correspondence: Dr. Ganesh Dangal MBBS; MD Chief, Gynaecological Oncology BPK Memorial Cancer Hospital, Chitwan, Nepal. Assistant Professor, Dept. of Obstetrics and Gynaecology College of Medical Sciences, Bharatpur, Nepal. Phone 00977-56-24501 Ext. 9116 Fax 00977-56-23747 E-mail gareshma@hotmail.com ABSTRACT: A prospective study at Thapathali's Maternity Hospital over a two and half months' period in the year 1998/99 was performed to study the relationship of Bishop score prior to induction of labour with the outcome of induction by oxytocin infusion and amniotomy in the active stage of labour. Hundred and three women were included in the study, 48 were in the low BS group and 55 were in the high BS group (study groups). There were no significant differences in maternal demographic features like age, gestational age, socio-economic status etc. between the two Bishop score categories. All women undergoing induction had a maternal or fetal indication for delivery and the indications did not differ among the two Bishop categories. The Apgar score at 1 and 5 minute did not differ significantly in both the study groups. The low Apgar score (0-3) at 1 min was found in 3.7% and 4.0% in the low BS and in the high BS groups respectively. Among the babies, 30% in the low BS group required baby unit admission as compared to 20% in the high BS group. The differences between both the groups were not significant statistically. More babies in the low BS group needed SCBU admission (30% Versus 20%) and more stayed longer as compared to the high BS group, but these differences were insignificant statistically. Neonatal outcome was satisfactory in the present study Keywords: Fetal outcome, Induction of labour, Bishop score, Apgar score. INTRODUCTION: Induction of labour implies stimulation of contractions before spontaneous onset of labour; with or without amniotomy.1 The state of the cervix is the most important predictor of success of induction. E.H. Bishop in 1964 devised a useful practical scoring system to assess the state of the cervix prior to the induction of labour.2 Despite the safety of induction, a liberal induction policy leads to an increase in operative deliveries creating potential risks for the mother and the child and greater expense. In addition to this, failed induction may be associated with a poor neonatal outcome and/or long labour with physical and emotional disturbances for the mother.3 The purpose of this study was to know the fetal outcome of induced labour in our pregnant women and to compare the results between the women with an unfavourable (Bishop score£4) and a favourable cervical score (Bishop score>5-8). materials and methods: This study was a hospital based prospective analytical study. It was conducted at Maternity hospital located at Thapathali, Kathmandu. It has 302 beds, where total number of delivery is around 14000 each year and a caesarean rate of 9.6% 4, 5 The duration of the study was two and a half months, starting from 31 July, 1998 to 15 Sept. 1998 and 16 May 1999 to 15 June 1999. All pregnant women except grand multipara (>4 viable deliveries) with alive singleton pregnancy of gestational age of 37 or more weeks with cephalic presentation were included in the study. Women with pre-labour rupture of membranes (PROM) and /or previous caesarean delivery were excluded from the study. These patients were categorized by Bishop scores at the beginning of induction for comparison of pregnancy outcome. Women undergoing induction with low Bishop scores (0-4) were grouped in one study group, and those with high Bishop scores (5-8) into another. Induction procedure: All the patients were induced by oxytocin infusion according to the Maternity hospital protocol.5 None of the subjects received prostaglandin gel to ripen the cervix and none were given epidural analgesia during labour. In the present study the traditional protocol of high dose oxytocin infusion by titration method until adequate contractions occurred was utilized by using a standard administration-set, 15 drops per minute equals a rate of 1 ml. per minute. None were monitored by CTG and fetal blood sampling (FBS). If membranes had not ruptured spontaneously, artificial rupture of membrane was generally performed when the cervix was 3-4 cm dilated in established active labour. At delivery, condition of the babies was assessed in terms of Apgar score at one and five-minutes, birth weights were taken and immediate neonatal nursing care provided. The mothers and their babies were followed-up till their discharge from the hospital. Premature babies, low birth-weight babies and babies with hypoxic ischaemic encephalopathy (HIE) were admitted in the SCBU. Perinatal morbidity was measured in terms of admissions to Special Care Baby Unit (SCBU). Details of obstetric history, examination, age, parity, gestational age assessment, cervical scores (BS), indications of induction, fetal condition in labour, neonatal outcome were documented. Data analysis was done manually and tests of significance were performed by EPI-INFO software. A two tailed P value less than 0.05 was considered to indicate a significant difference.6 RESULTS: Over the two and a half months' study period 103 women underwent induction of labour, 72 (70%) were nulliparas and 31 (30%) were multiparas. . The induction rate was 3.7%. Forty-eight (46.6%) women had low BS (0-4), whereas fifty-five (53.4%) had high BS (5-8). The mean BS in low BS group and high BS group was 3.72 and 6.01 respectively. TABLE I: PATIENTS CHARACTERISTICS
Numbers in parentheses indicate numerator and denominator of percent. NS: Not Significant S: Significant There were no differences between the two study groups with regards to maternal age, gestational age at induction, antenatal attendance and socio-economic status. TABLE II: INDICIATIONS FOR INDUCTION IN RELATION TO BISHOP SCORE
Post-dates (Overdue by dates, post - EDD) was the leading indication for induction, comprising of 64.58% women among low BS group and 76.36% women in high BS group. The indications were similar in both the study groups, the difference being not significant statistically. TABLE III: APGAR SCORE AT BIRTH IN RELATION TO BISHOP SCORE (at one minute)
•· Data presented as percent of total numbers of cases in each group. The majority had good Apgar score (7-10) at 1 minute, i.e. 52% in the low BS group and 66% in the high BS group. However, the difference was not significant (P=0.2244). Very low Apgar score (0-3) at one minute was found to be 3.7% and 4.0% in the low BS group and in the high BS group respectively. There was also no significant difference in between the groups (P=0.9488). TABLE IV: APGAR SCORE AT FIVE MINUTES IN RELATION TO BISHOP SCORE
•· Data presented as percent of total numbers of cases in each group. None had very poor Apgar score at 5 minutes in either group. Only 4% had an Apgar score of 4-6 in the high BS group but none in the low BS group. The difference was insignificant (P=. 5386). Cent percent in the low BS group and 96% in the high BS group had good Apgar score (7-10). The difference was insignificant too (P=. 5386). TABLE V: SCBU (BABY UNIT) ADMISSIONS IN RELATION TO BISHOP SCORE
•· Data presented as percent of total numbers in each group. •· No SB/NND/Congenital anomaly observed. Only about 20% new-borns needed baby unit admission; very few (i.e. 7.7%) needed longer stay of > 24 hours in the baby unit. In the low BS group, 29.6% needed admission; half of them (i.e. 14.8%) needed longer stay, whereas in the high BS group, only 16% needed admission, and 1/4 (i.e. 4%) needing longer stay. So, more babies in the low BS group needed SCBU admission and more stayed longer as compared to the high BS group. But these differences were not significant statistically. DISCUSSION: In the present study with the induction rate of 3.7%, fetal outcome of induction of labour was studied. The rate of induction varies greatly. A rate of 4% in one centre in Britain compared to 40% in another centre exemplifies the variation.7 The reason for a low rate in our study was not clear but it might be due to obstetricians' reluctance of induction unless there is a valid indication. Indications for induction of labour are fetal, maternal or both and at times social. Fetal reasons constitute the large majority of indications. The fear of poor perinatal outcome in epidemiological studies is more often an important factor. The indications for induction of labour in the present study are shown in table II. In the present series, the major indication for induction was post-dated pregnancy with a 70.8% of all induced labours followed by HDP (11.6%), niggling pain (10.6%), less fetal movement (4.8%) and others (1.9%). The indications did not differ significantly by Bishop category in both the study groups. In this study, post-date was major indication. This might be due to the practice of early induction at 40+ weeks by the obstetricians, which may be because of lack of facilities for intensive fetal surveillance for post-dated pregnancies. The fetal/neonatal outcome in induced labour was generally good with no stillbirth and early neonatal deaths but induction of labour in the presence of an unripe cervix (cervical score <3) results in a longer labour and a higher incidence of CS and fetal asphyxia.8 In the present study there was no stillbirth and early neonatal death. The babies did not have any congenital anomalies and Apgar score of 7-10 at one minute was found to be in 52% in the low BS group and 66% in the high BS group. The difference was not significant statistically. Very low Apgar score of 0-3 at one minute was found to be in 3.7% in the low BS group and 4% in the high BS group and the difference was also insignificant. Similarly, Apgar score of 7-10 at 5 minute was found to be cent percent in the low BS group, and 96% in the high BS group. None had a very poor (0-3) Apgar score at 5 minutes in either group. Regarding the baby unit admission, the majority did not need SCBU admission, only about 20% new-borns needed admission; very few (i.e. 7.7%) needed longer stay of > 24 hours in the baby unit, and there was no significant difference between the study groups regarding the SCBU admission and the duration of stay. Macer JA et al in their study found that all babies were born alive and there were no neonatal deaths in the induction group. Neonatal intensive care unit admission was only in 0.8% babies.9 In a study the neonatal outcome was reported to be good with 5 minute Apgar score of < 7, only in 3.2% babies of women induced by traditional oxytocin protocol.10 In a few studies, neonatal hyperbilirubinamia and neonatal sepsis were found in cases of induced labour.11, 12 In another study, one minute Apgar score < 5 was found in 23% and 6% patients with cervical score of 0-3 and 4-7 groups respectively.8 Women with poor cervical score had a poor neonatal outcome in a Singaporean study in which one minute and 5 minute Apgar score was slightly but not significantly lower in those with poor cervical scores, especially in multigravidas only 4.7% neonates were admitted to the SCBU.13 Neonatal outcome was satisfactory in the present study with no still birth and early neonatal death in the induced labour. The babies born to the women with a low Bishop score had higher special care baby unit admission rate but the outcome was not different significantly between the study groups. REFERENCES •1. Cunnigham FG, MacDonald PC, Gant NF, Leveno KJ, Gilstrap III LC, Hankins GDV, Clark SL (eds). Williams Obstetrics, 20th edition. Connecticut: Appleton and Lange 1997: 415- 458. •2. Bishop EH. Pelvic scoring for elective induction. Obstet Gynaecol 1964; •3. Biswas A, Arulkumaran S. Induction of labour. In : Arulkumaran S, Ratnam SS, Rao KB (eds). The management of labour. Chennai: Orient Longman Ltd. 1996: 213-227. •4. Department of Statistics. Statistics report of 2055. Thapathali: Maternity Hospital. 5. Sharma S. DIGDARSHAN, 1st edition. Thapathali: Paropakar Shree Panch Indra Rajya Laxmi Devi Prasuti Griha Development Board 1999: 2-6. 6. Mahajan BK. Methods in biostatistics, 5th edition. New Delhi: Jaypee Brothers 1989. •7. Pearson JF, Andrew J. Induction of labour. The case for low rate. In: Beard RW, Paintin DB (eds). Outcome of obstetric intervention in Britain. London: RCOG Publication 1980: 137-149. •8. Calder AA. The human cervix in pregnancy: a clinical perspective. In: Ellwood DA, Anderson ABM (eds). The cervix in pregnancy and labour: Clinical and biochemical investigations. Edinburgh: Churchill Livingstone 1981: 103-122. •9. Macer JA, Macer CL, Chan LS. Elective induction versus spontaneous labour: A retrospective study of complications and outcome. Am J Obstet Gynaecol 1992; 166 (6): 1690 -1697. •10. Mercer B, Pilgrim P, Sibai B. Labour induction with continuous low-dose oxytocin infusion: A randomised trial. Obstet Gynaecol 1991; 77 (5): 11. Hendricks CH. Second thoughts on induction of labour. In: Studd JW (ed). Progress in obstetrics and gynaecology vol-3. Edinburgh: Churchill Livingstone 1983: 101-112. 12. Cummiskey KC, Dawood MY. Induction of labour with pulsatile oxytocin. Am J Obstet Gynaecol 1990; 163: 1868-74. 13. Arulkumaran S, Gibb DMF, Tamby Raja RL, Heng SH, Ratnam SS. Failed induction of labour. Austr NZ J Obstet Gynaecol 1985; 25 (3): 190-193.
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