Purpose: To analyse the significance of risk factors and the possibility of prediction of shoulder dystocia.
Methods: This was a retrospective cohort study. There were 9,767 vaginal deliveries at 37 and more weeks of gestation analysed during 2005-2007. Studied population included 234 deliveries complicated by shoulder dystocia. Shoulder dystocia was defined as a delivery that required additional obstetric manoeuvres to release the shoulders after gentle downward traction has failed. First, a univariate analysis was done to identify the factors that had a significant association with shoulder dystocia. Parity, age, gestation, induction of labour, epidural analgesia, birth weight, duration of second stage of labour and mode of delivery were studied factors. All factors were then combined in a multivariate logistic regression analysis. Adjusted odds ratios (Adj. OR) with 95% confidence intervals (CI) were calculated.
Results: The incidence of shoulder dystocia was 2.4% (234/9,767). Only mode of delivery and birth weight were independent risk factors for shoulder dystocia. Parity, age, gestation, induction of labour, epidural analgesia and duration of second stage of labour were not independent risk factors. Ventouse delivery increases the risk of shoulder dystocia almost 3 times, forceps delivery comparing to the ventouse delivery increases risk almost 3.4 times. Risk of shoulder dystocia is minimal with the birth weight of 3,000 g or less.
Conclusion: It is difficult to foretell the exact birth weight and the mode of delivery, therefore occurrence of shoulder dystocia is highly unpredictable. Regular drills for shoulder dystocia and awareness of increased incidence with instrumental deliveries are important to reduce fetal and maternal morbidity and mortality.