Randomised controlled trials (RCTs) that compared hygroscopic dilators (laminaria, lamicel or dilapan) with vaginal prostaglandins were eligible for inclusion, provided the interventions were used for induction of labour in singleton pregnancies with vertex presentation at term (at least 37 weeks’ gestation). It was required that the foetus was not showing signs of hypoxia at the time of induction. The primary review outcome was vaginal delivery. Secondary outcomes were maternal morbidity (endometritis or chorioamnionitis), neonatal morbidity (neonatal sepsis, need for assisted ventilation, intensive care admission or death) and rate of emergency caesarean sections due to foetal heart rate change.
Participants in the included studies were primiparous women. The studies used laminaria, lamicel or dilapan administered for differing lengths of time. Prostaglandin dose varied from 0.5μg to 4mg administered as either gel or pessaries. Maternal morbidity was reported at six weeks post partum. Definitions of maternal and neonatal morbidity varied across the studies (where reported).
The authors stated neither how the papers were selected for the review nor how many reviewers performed the selection.