Cerclage After Full Dilatation Caesarean Section

CRAFT-OBS Inclusion Criteria: * Pregnant women under 23+6 weeks gestation with a history of previous caesarean section in labour. * Singleton pregnancy. * Willing and able to give informed consent (with or without interpreter). Exclusion Criteria: * Under 16 years of age. * Inability to give informed consent. * Previous caesarean section carried out before labour. * Women who have been commenced on management with progesterone, a cerclage or arabin pessary as part of their care or another research study CRAFT-RCT: Inclusion criteria: * Pregnant women up to 23+6 weeks gestation with a history of FDCS. * Short cervix (\<=25mm) on transvaginal ultrasound scan. Exclusion criteria: * Women with persistent fresh vaginal bleeding evident on speculum examination. * Women with visible fetal membranes evident on speculum examination or open cervix on ultrasound scan. * Women with severe abdominal pain/evidence of sepsis (as judged by attending clinician). * Known significant congenital or structural or chromosomal fetal abnormality. * Suspected or proven rupture of the fetal membranes at the time of recruitment. CRAFT-IMG Inclusion criteria: * Pregnant women between 14+0 and 23+6 weeks gestation with a history of FDCS. Exclusion criteria: * Contraindications to MRI, e.g. claustrophobia, BMI \>40 kg/m2 (due to technical limitations of scanner) or a women with a non-MRI compatible metallic implant.