Study design and setting 

A retrospective cross-sectional study was employed from 2012 to 2015 in Wolaita Sodo University teaching referral hospital. The hospital is located in Wolaita zone of southern nations nationalities and people’s regional state; 327 km from the capital Addis Ababa. Established in 1928, the hospital is currently serving more than 2 million people with about 195 inpatient beds. 

Sampling and sample size

Single population proportion formula was used to calculate the sample size with the assumptions 0.05 significance level, 66.9% proportion of labor induction success (Barthélémy et al., 2013), 5% margin of error and 10% nonresponse rate. The final sample size was calculated to be 347. All women with induction of labor from registration book were selected back starting from 2015 to 2012 until desired sample size was achieved.

Data collection tool and procedure

The study included all registered women who had been delivered a gestational age of 28 weeks and above through induction of labour. Data were collected using a pretested structured questionnaire from the induction register and medical record files. Information regarding demographic features, details of induction of labour (indication, method, mode of delivery, complications, and neonatal outcome). Seven midwifery nurses guided by three supervisors collected the data on January 7, 2012. 

Data processing and analysis

The filled questionnaires were checked for completeness and entered into EPI INFO version 3.5.3 statistical software and then exported to SPSS version 21 for further analysis. Descriptive statistics was used to describe the study population in relation to relevant variables. Both bivariate and multivariate logistic regression models were used to identify associated factors. Odds ratios and their 95% confidence intervals were computed and variables with p - value less than 0.05 were considered as significantly associated with the outcome variable. 

Ethical consideration

Ethical clearance was obtained from the college of health sciences and medicine, Wolaita Sodo University. A formal letter of cooperation was written to the hospital. Anonymity was maintained to assure confidentiality.

Data quality assurance 

Data quality was controlled by giving trainings and appropriate supervisions for data collectors. A pre-test was conducted on 5% of the records that are not included in the study. Appropriate modifications were made after analyzing the pretest result before the actual data collection. 

Operational definitions 

Induction of labour 

Initiation of uterine contractions prior to its spontaneous onset after 28 weeks of gestation. 

Failed induction of labour 

Failure to achieve a vaginal delivery within 12 h after induction of labour was commenced. 

Successful induction of labour

When a woman had achieved vaginal birth within 12 h after induction of labour was started.

Fetal heart rate non-reassuring

Fetal heart either below or above normal range following induction of labour

Induction of labour is one of the fastest growing medical procedures in current obstetric practice. In this study out of five  women  who  undergone  induction,  three of them had successful induction. This finding was similar with study done in Nepal (Rayamajhi et al., 2009) and Congo (Barthélémy et al., 2013) where 65.38 and 66.9% of the participant undergone successful induction. In other way successful induction rate in this study was lower than study conducted in Saudi Arabia (Ghadeer et al., 2012) and Pakistan (Neelofur et al., 2012) in which 84 and 81.9% of women had successful outcome of IOL respectively. This discrepancy may be due to difference in quality of induction care provided by the hospitals. 

Various methods have been recommended for induction of labour such as intra-cervical Foleys balloon, prostaglandin E2 and intra venous Oxytocin etc. In this study oxytocin IV infusion was used exclusively to induce induction. This finding was comparable with study done in Latin America (Guerra et al., 2009) where oxytocin IV infusion was used in about 90% of all labour inductions. This is also in agreement with other studies that have reported its use in 85-100% of inductions (Goffinet et al., 2003; Vahratian et al., 2005; Le Ray et al., 2007). But in study conducted in Egypt, 65.5% of the women received vaginal misoprostol while only 34.4% received intravenous oxytocin infusion as a method of labour induction. The decision whether to induce with oxytocin or misoprostol was probably not dependent on the favorability of the woman’s cervix, but more on their availability and culture within the unit. 

According to this study the primary reason for induction of labour was premature rupture of membranes followed by post-date and medical disorders with pregnancy. This finding was in line with study done in Egypt (Mohamed et al., 2013). Premature rupture of membranes was also found to be the commonest indication for induction of labour in study done on unmet need for induction of labour in Africa (Fawole et al., 2012). In other study done in Saudi Arabia (Ghadeer et al., 2012) post-term pregnancy was found to be the most common indications. While the common indications for induction in Nepal study was post term pregnancy (Rayamajhi et al., 2009).

In this study it was found that, age was significant predictor for success of labour induction, its likelihood being greater among women of age less than 24 years; which is similar with study from Nepal (Rayamajhi et al., 2009). The condition of the cervix at the start of induction is an important predictor, with the modified Bishop score being a widely used and predominant risk factor scoring system (National Collabourating Centre for Women’s and Children’s (NCC-WCH), 2008) induction of labour results in high failure rate if the cervix is not ripe or vice versa (SOGC Clinical practice guidelines, 2001).

In line with these studies, the current finding also showed strong association between bishop score and successful induction of labour. The odds of successful induction  were  7 times more likely in women with Bishop Score above 5. Similarly study conducted at Kathmandu medical college teaching hospital to assess indications for labour induction and predictors for failed induction the 0-5 Bishop Score group accounted for the majority of failures 70.1% (Arulkumaran et al., 2008). Other study conducted to quantify the risk of cesarean delivery associated with medical and elective induction of labor, Bishop score of 5 or less was a predominant risk factor for a CS (Vrouenraets et al., 2005). In study that examines influence of labor induction on obstetric outcomes in patients with prolonged pregnancy, the Bishop score before induction was an important factor that affected the delivery outcome, resulting in significantly higher rates of cesarean section and vacuum extraction when the score was unfavorable (Bodner-Adler et al., 2005).

In Ethiopian study done to evaluate the relation of Bishop Score and induction outcome measured by length of induction initiation-vaginal delivery time and modes of delivery, 45.7% induction failures was observed among the 0-5 Bishop score group (Berhan and Dwivedi, 2007). Apgar score at first and fifth minute was found to be one of indicators of successful induction related to the baby.

Pervious study done in Latin America has shown that induction was associated with lower 5th minute Apgar scores. In our study even though Apgar score at fifth minute did not show significant association, the success of induction  of  labour  has increased as first Apgar score become greater than 7.