[Truncated abstract] This thesis explores the risk factors and perinatal outcomes associated with prelabour rupture of membranes, with a particular focus on the environmental context. Prelabour rupture of membranes is defined as the rupture of fetal membranes before the onset of labour. It is a relatively common obstetric endpoint, occurring in approximately 8-10% of pregnant women at term (PROM) and in up to 40% of all preterm deliveries (pPROM). Despite the high prevalence of the condition, the biological mechanisms and risk factors, and in particular the role of environmental predictors, behind the development of PROM and pPROM remain largely unclear. A record-based prevalence design was used to analyse a population of 16,229 nulliparous, Caucasian women residing in Perth, Western Australia who gave birth to a single newborn during 2002-2004. Maternal age, socioeconomic status and threatened preterm labour during pregnancy were identified as risk factors for prelabour rupture of membranes. Term PROM was significantly associated with fetal distress (OR 1.19; 95%CI 1.00-1.43) and post-partum haemorrhage (OR 1.99; 95%CI 1.60-2.48). A number of perinatal complications were observed to be associated with the presentation of preterm PROM, including prolapsed cord (OR 13.95; 95%CI 4.57-42.61), ante-partum haemorrhage (OR 3.29; 95%CI 2.20-4.91), post-partum haemorrhage (OR 2.12; 95%CI 1.54-2.91), low birth weight (OR 17.79; 95%CI 13.87-22.82), very low birth weight (OR 20.01; 95%CI 14.12-28.35) and stillbirth (OR 5.42; 95%CI 2.87-10.21). However, the outcomes were similar between pPROM patients and other preterm deliveries, indicating that the complications arose due to the timing of the delivery. In contrast though, the risk factors between the two outcomes varied which may suggest that a different aetiological pathway exists between preterm PROM and other preterm deliveries. The frequency of complications decreased with increasing gestational age at delivery until the pregnancy reached full-term, whereupon an increase in gestational age at delivery resulted in an increased risk of fetal distress and post-partum haemorrhage. This finding is novel and may have important implications for the management of prelabour rupture of membranes, specifically with regard to the relative risks and benefits of expectant management (that is, the patient is admitted to an obstetric facility or hospital and closely monitored) versus planned delivery. ... This study represents the first attempt to investigate the potential associations between environmental risk factors and prelabour rupture of membranes. The results of the thesis provide a substantial contribution to our knowledge on prelabour rupture of membranes, including findings of direct relevance to clinical practice as well as a potentially contributing environmental exposure pathway. These original findings suggest a possible preventative approach to reducing the occurrence and associated morbidity of prelabour rupture of membranes may be feasible, and should be pursued if future research confirms the preliminary findings of this thesis.