Developing a core outcome set for research in multiple pregnancies

The incidence of multiple pregnancies varies worldwide from approximately 6.7 to 40 per 1000 births but is universally increasing. Irrespective of incidence, all multiple pregnancies are at higher risk compared to singleton pregnancies, and present unique perinatal dilemmas. With the increasing use of assisted reproductive techniques these problems will continue to increase. Fetal complications of multiple pregnancy include: intrauterine growth restriction, congenital abnormalities, single and double intrauterine demise, preterm delivery (spontaneous and iatrogenic) with the associated consequences of prematurity including neonatal death or long-term neurological sequelae. There are also complications unique to monochorionic multiple pregnancies such as twin-twin transfusion syndrome and twin-reversed arterial perfusion. In addition, mothers are at increased risk of many obstetric complications including: pre-eclampsia, gestational diabetes, anaemia, haemorrhage, postnatal depression, and maternal death. Multiple pregnancy can also have profound psychological effects on parents, irrespective of pregnancy outcome, both antenatally and postnatally. We aim to develop a core outcome set for research in multiple pregnancies, irrespective of chorionicity.


Dr R. Katie Morris (PI), University of Birmingham
Professor Mark D Kilby, University of Birmingham
Professor Khalid Khan, Queen Mary University of London

Clinical Research Fellow:
Dr Fiona L Mackie, University of Birmingham

Further Study Information

Current Stage: Completed – pending publication
Date: September 2016 - September 2022
Funding source(s): To be confirmed

Health Area

Disease Category: Pregnancy & childbirth

Disease Name: Multiple pregnancies

Target Population

Age Range: 18 - 60

Sex: Female

Nature of Intervention: Any

Stakeholders Involved

- Clinical experts
- Consumers (patients)
- Families
- Patient/ support group representatives
- Researchers

Study Type

- COS for clinical trials or clinical research


- Consensus meeting
- Delphi process
- Survey
- Systematic review

Firstly we will perform a systematic review of existing studies on multiple pregnancies to delineate the fetal, neonatal and maternal outcomes most commonly reported. We will then conduct a Delphi survey of stakeholders (parents, support group representatives, obstetricians, neonatologists, midwives, researchers) to formulate a consensus of core outcomes and refine the list from the systematic review. The final core outcome set will be confirmed at a consensus meeting.