Predictors Of Successful Induction Of Labour In Post-term Pregnancies At Kenyatta National Hospital
Abstract
Background: A post-term or prolonged pregnancy according to World Health Organization (WHO) is one that has exceeded 294 days from the last normal menstrual period. A prolonged pregnancy can lead to post-maturity of the fetus posing a great threat to its further survival in-utero and multiple complications including neonatal mortality post delivery. World-wide 5-10% of all pregnancies are prolonged with 20% of post-term fetuses having dysmaturity syndrome. The incidence of induction is on the rise, half of which are due to post-dates. At Kenyatta National Hospital the rate of induction of labour due to prolonged pregnancies stands at 50 % of all inductions. The failure of induction world-wide has been increasing and it is therefore important to determine some of the predictors of successful induction. Several studies have been done world-wide to predict factors influencing failed induction but there has been none specifically for predictors of successful induction in post-dates.
Objectives: To determine the predictors of successful induction of labour in post-term pregnancies at Kenyatta National Hospital.
Study design: Descriptive cross-sectional study among post-term pregnant women delivering at Kenyatta National Hospital (KNH).
Study setting: The labour ward and post-natal wards at Kenyatta National Hospital
Study participants: 188 post-term pregnant women, with a live fetus undergoing induction of labour with no alternate indication for induction.
Methodology: This was a descriptive cross-sectional study on post-term pregnant women admitted for labour induction at Kenyatta National Hospital between January and April 2013. 188 patients with gestational age of ≥ 41 weeks undergoing induction of labour during the study
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period were consecutively recruited into the study until the sample size was reached. A questionnaire was used to obtain data about the socio-demographics, gestational age and parity. The pre-induction Bishop Score, the birth weight of the infant, methods of induction and the outcome of the induction process was availed from the patients file.
Results: A total of 188 women were induced due to post-term pregnancies. Most of the participants (76%) were aged between 20 and 29 years. Majority of the women were primi-gravidae (58%), and the mean gestational age was 41.14 weeks (range 41-42 weeks). The success rate of induction among study participants was 68 %. Prostaglandins in combination with artificial rupture of membranes and Oxytocin infusion was the most common method used for inducing labour. Multiparity and a favourable Bishop score were significant predictors of successful induction in post-term pregnancies. Bishop scores ≥6 were associated with higher success rates for labour induction (85.2%) versus 60.4% in those with lower Bishop scores. Infants less than 4000grams had higher rates of vaginal deliveries (72.8%) compared to those with more than 4kgs (6.7%). Age of the patient and the modality of induction were not determining factors in induction of post-term pregnant women in this study.
Conclusions and recommendations: In conclusion Bishop score of ≥ 6, multi-parous patients and mothers with infants having a birth weight of < 4000grams had a higher rate of successful induction. A pre-induction estimated fetal weight should be a routine practice to select the right patients for the induction process. Mothers with estimated fetuses over 4000grams should be offered an elective caesarean as an option.
Citation
Master of Medicine in Obstetrics and GynaecologyPublisher
University of Nairobi