Observational Study; To evaluate subsequent pregnancy risk of preterm birth in women with a history of the previous caesarean in established labour. This prospective study using clinically acquired cervical length and quantitative fetal fibronectin data will help establish a predictive model of preterm birth <34 weeks and <37 weeks.
OBS-CTL (control group): To assess the risk of preterm birth or late miscarriage in women at study sites following only term vaginal delivery/(ies) and compare to the OBS cohort.
Imaging sub-study; To aid understanding of micro and macrostructural features within the cervix which predisposes to preterm birth in women with a previous full dilatation caesarean section. This will use MRI and an advanced transvaginal ultrasound protocol and assess if structural changes can be visualised in the cervix.