Recipient organisationNIHR University College London Hospitals Biomedical Research Centre
NIHR supportRecorded as supported by this research centre
PeriodJan 2025 — Jun 2025
In plain English
AI plain-English summary
Every year, around 120 women in the UK face a devastating choice when one twin in a shared placenta stops growing properly before 24 weeks of pregnancy. Doctors currently have no clear evidence on whether to intervene early—with laser surgery to separate the twins’ blood supply—or to monitor the pregnancy closely and only act if complications arise. This uncertainty matters because early-onset selective fetal growth restriction in monochorionic twins carries high risks of stillbirth, brain injury, or severe disability for one or both babies. The FERN study will track 120 women across 15 UK fetal medicine units, recording what management strategies doctors actually use and what happens to the babies. Researchers will also interview 25 parents and 25 clinicians to understand the ethical dilemmas and practical barriers to running a proper trial. If this feasibility study succeeds, it will lay the groundwork for a definitive UK trial comparing active intervention against expectant management. That future trial could give obstetricians and parents the first reliable evidence to guide decisions in these high-stakes pregnancies, potentially reducing death and long-term harm for the most vulnerable twins.
View original technical description
Monochorionic (MC) twin pregnancies complicated by selective fetal growth restriction (sFGR) have high rates of fetal morbidity and mortality and at present there is a lack of evidence to inform the best way of managing such pregnancies, especially where this happens early in pregnancy. FERN, a prospective UK multicentre study, aims to determine the feasibility of conducting a trial of active intervention versus expectant management in sFGR in MC twins whilst also examining women’s and clinician’s preferences, ethical dilemmas, current UK practice, cases number per year, natural history of sFGR and key elements of a potential future trial design. To achieve these aims the study will use a mixed methods approach of 3 work packages. Work Package 1 will build on experiences from our recent survey of practice and the Twins Trust supported Twin-to-Twin Transfusion Syndrome registry to collect prospective data on pregnancy management and clinical outcomes. 15 UK Fetal Medicine Units will recruit 120 women with an MC twin pregnancy affected by early onset (prior to 24 weeks) sFGR. We will assess management strategies and clinical outcomes from routine practice to determine the natural history of sFGR, distribution of interventions and pregnancy outcomes. Work Package 2 will assess 25 parent’s and 25 clinician’s preferences via interviews and focus groups to identify ethical concerns and barriers to randomisation to management options. Work Package 3 will utilise the information provided in work packages 1 and 2 to develop a consensus on a future definitive study. We will use Delphi methodology involving all stakeholder groups (patients, clinicians, funders, charities) to reach a consensus over two rounds. If appropriate, we will then be able to propose a trial of active intervention versus expectant management for sFGR in MC twin pregnancy.
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