Induction of labour is considered justified when the benefits of prompt delivery outweigh the consequences of Caeserian Section (CS). Literature on the effectiveness and safety of surgical induction of labour in term and postdated pregnancy is limited in Bangladesh. This study was aimed to assess the effectiveness and safety of surgical induction of labour in term and postdated pregnancy. This prospective clinical study was conducted in the in-patient Department of Obstetrics and Gynecology, Combined Military Hospital (CMH), Dhaka from July, 2005 to June 2006. A total of 100 pregnant women with term and postdated pregnancy were selected for the study by simple random sampling. The particulars of the patient, detailed menstrual and obstetric history, induction delivery interval, mode of delivery and foetal outcome and maternal complications were recorded. The results were analysed by Statistical Package for Social Science (SPSS) version 16.0. The mean ± SD age of the participants was 25.79 ± 6.16 years with a range of 18 – 38 years. The indication of Induction of labour included term pregnancy (79%) and postdated pregnancy (21%). Normal vaginal delivery was done in 78% cases, CS in 17% cases and vacuum extraction in 5% cases. Ninety three percent babies were born healthy, 6% were asphyxiated, perinatal death 2% and still born 1%. O₂ inhalation was needed for 6% babies. Prolonged second stage (7%), post-partum haemorrhage (8%), maternal distress during labour (10%) and manual removal of placenta (12%) were the observed maternal complications. No significant difference was observed between term and post term pregnancy in the term of normal vaginal delivery, vacuum extraction and lower uterine cesarean section. Induction of labour is beneficial for both term and postdated pregnancy with associated complications. Foetal outcome was good and maternal complications were acceptable.

Keywords: Surgical induction of labour, Post dated, Bishop's score Foetal outcome

Jump to Section -------------------- Top of Page Abstract Introduction Materials and Methods Results Discussion References

Introduction

Induction of labour (IOL) is the stimulation of regular uterine contraction before the spontaneous onset of labour using mechanical or pharmacological methods in order to generate progressive cervical dilatation and subsequent delivery.¹ For induction of labour, the benefits of early delivery to either mother or fetus should outweigh the risks of pregnancy continuation.² The incidence of labour induction has continued to rise over the past several decades.³ The rate of labour induction varies from 9.5 – 33.7% of all pregnancies annually.⁴ Labour induction rates present a wide country variation and also present among obstetric units in the same geographic region or practitioners within the same hospital. This variability is the result of differences in the obstetric protocols or the judgment of the individual physician regarding the appropriateness of obstetric interventions.⁵ In developed countries, the number of infants delivered at term following induction of labour can be as high as one in four deliveries.⁶ The World Health Organization (WHO) Global Survey on Maternal and Perinatal Health, conducted in 24 countries which included nearly 3,00,000 observations, showed that 9.6% of them were delivered by labour induction. The survey found that African countries have lower rates of induction of labour (lowest: Niger 1.4%) compared with Asian and Latin American countries (highest: Sri Lanka 35.5%).⁷ The rate of induction in Canada has increased steadily from 12.9% in 1991 – 1992 to 19.7% in 1999 – 2000. The rate reached a high of 23.7% in 2001 – 2002, decreased slightly to 21.8% in 2004 – 2005, and since then remained steady.⁸

However, all inductions are not successful and some may develop complications. In nullipara with an unfavorable cervix undergoing labour induction, caesarean delivery rate is more than 30%.⁹ The increased risk of caesarean section after induced labour is well documented, but such obstetric intervention is considered justified when the benefits of prompt delivery outweigh the consequences of a caesarean section. Conditions such as postterm pregnancy, hypertensive disorders, intrauterine growth restriction and diabetes are commonly accepted indications for induction.² The increased frequency of obstetric interventions, such as induction of labour, appears to have contributed to the current trends in caesarean rates.¹⁰ It is associated with doubling in caesarean section delivery rate compared with spontaneous labour.¹¹

However, there is evidence for an increase in the frequency of labour induction without any such agreed upon indication. This situation might lead to unnecessary caesarean deliveries and, consequently to a high risk of adverse outcomes for the mother and the child .¹² In the absence of a well-established clinical indication, the contribution of labour induction to caesarean rates among low-risk nulliparous women can approach 20%.¹³ Additionally, labour induction in itself increases in-hospital predelivery and labour time and costs beyond those that are related to surgery.¹⁴

Indications and contraindications for induction should be reviewed. Risks and benefits of labour induction should be discussed with the patient and relatives including the risk of cesarean delivery. Confirmation of gestational age is very important and fetal lung maturity status should be performed if indicated.² Routine antenatal ultrasound for confirmation of expected date of delivery has been shown to reduce induction rates for post dates (41+0 weeks) pregnancies after correction of dates.¹⁵ A cervical examination should be performed and documented (Bishop score). Foetal presentation and position should be confirmed. Clinical pelvimetry should be performed and cephalopelvic disproportion (CPD) should be ruled out. According to WHO guidelines, labour induction should be performed at a center, where qualified staff and OT facilities are available for cesarean section. Uterine activity and electronic fetal monitoring (EFM) should be done for all patients undergoing labour induction.²

Some of the methods of IOL are still used in current practices. Other methods such as vaginal or uterine douches, stimulant injections thrown into the rectum, and the use of ergot alkaloid have been abandoned because of their "ineffectiveness or poisonous effects on the infant″¹⁶ Prostaglandins act on the cervix to enable ripening by a number of different mechanisms. Multiple other agents have been advocated for cervical ripening, use of Foley′s catheter is a favoured method in low resource setups.¹⁷ Misoprostol is an effective agent for cervical ripening.¹ Dinoprostone has been approved by FDA for cervical ripening in women at or near term with mean induction-delivery interval of 15.6 + 0.7 hours.¹⁸ Surgical induction of labour comprises artificial rupture of membrale (ARM) and stripping the membrane. These are the most commonly performed procedures in obstetrics for induction of labour. There is evidence that routine sweeping (stripping) of membranes promotes the onset of labour and that this simple technique decreases artificial rupture of membrale (ARM) rates. It is believed that the technique results in an increase of local production of prosglandins.¹⁹ Amniotomy can be a simple and effective component of labour induction when the membrane are accessible and the cervix is favourable. A 2007 cochrane meta-analysis of 17 trials with 2566 women measured the safety of amniotomy and intravenous oxytosin for induction of labour. Amniotomy alone resulted in fewer vaginal deliveries in 24 hours than amniotomy plus oxytocin. Amniotomy and oxytocin resulted in fewer instrumental deliveries than placebo.²⁰

Although it is well documented that induction of labour increases the risk of caesarean, however such obstetric intervention is considered justified when the benefits of prompt delivery outweigh the consequences of a caesarean section. Conditions such as post-term pregnancy, hypertensive disorders, intrauterine growth restriction and diabetes are commonly indications of IOL. Literature on the effectiveness and safety of surgical induction of labour in term and post-dated pregnancy is limited in Bangladesh. So, this study was undertaken to observe the effectiveness and safety of surgical induction of labour in term and post-dated pregnancy. The ultimate objective was to reduce the rate of caesarean section in term and post dated pregnancy, to avoid postmaturity and its consequences and to improve the fetomaternal outcome.

---