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Cognitive outcome in childhood of birth weight discordant monochorionic twins: the long-term effects of fetal growth restriction
  1. Ravi Shankar Swamy1,2,3,
  2. Helen McConachie4,
  3. Jane Ng5,
  4. Judith Rankin4,
  5. Murthy Korada6,
  6. Stephen Sturgiss7,
  7. Nicholas D Embleton4,8
  1. 1Department of Paediatrics, Imperial College London, London, UK
  2. 2Department of Neonatology, Imperial College Healthcare NHS Trust, London
  3. 3Department of Neonatology & Paediatrics, Manipal Hospitals and University, India
  4. 4Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK
  5. 5Cumming School of Medicine, University of Calgary, Calgary, Canada
  6. 6Ridge Meadows Hospital, Maple Ridge, Canada
  7. 7Department of Fetal Medicine, Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
  8. 8Newcastle Neonatal Service, Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
  1. Correspondence to Dr Ravi Shankar Swamy, Department of Paediatrics, Imperial College London, London W12 0HS, UK; doc_swamy{at}


Aim Intrauterine growth restriction (IUGR) is associated with poorer outcomes in later life. We used a monochorionic twin model with IUGR in one twin to determine its impact on growth and neurocognitive outcomes.

Methods Monochorionic twins with ≥20% birth weight discordance born in the north of England were eligible. Cognitive function was assessed using the British Ability Scales. The Strength and Difficulties Questionnaire was used to identify behavioural problems. Auxological measurements were collected. Generalised estimating equations were used to determine the effects of birth weight on cognition.

Results Fifty-one monochorionic twin pairs were assessed at a mean age of 6.3 years. Mean birth weight difference was 664 g at a mean gestation of 34.7 weeks. The lighter twin had a General Conceptual Ability (GCA) score that was three points lower (TwinL −105.4 vs TwinH −108.4, 95% CI −0.9 to −5.0), and there was a significant positive association (B 0.59) of within-pair birth weight differences and GCA scores. Mathematics and memory skills showed the largest differences. The lighter twin at school age was shorter (mean difference 2.1 cm±0.7) and lighter (mean difference 1.9 kg±0.6). Equal numbers of lighter and heavier twins were reported to have behavioural issues.

Conclusions In a monochorionic twin cohort, fetal growth restriction results in lower neurocognitive scores in early childhood, and there remain significant differences in size. Longer term follow-up will be required to determine whether growth or cognitive differences persist in later child or adulthood, and whether there are any associated longer term metabolic sequelae.

  • twins
  • monochorionic
  • cognition
  • intrauterine growth restriction

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  • Contributors RSS, NDE, JR, HM and SS conceived and designed the study. RSS and MK participated in the data collection. RS, NDE and JN performed the statistical analysis. JR and HM interpreted the data helped by SS. RSS and NDE wrote the manuscript. HM, JR, MK, SS and JN reviewed the manuscript and made significant changes. All authors read and approved the final manuscript.

  • Funding The Children’s Foundation, Newcastle upon Tyne.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval County Durham & Tees Valley REC 1 Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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