Underlying Mechanisms of SIDS – Investigation in to the Effects of Intra-uterine Growth Restriction on the Heart and Circulation

Dr. Emily Cohen was the recipient of a three-year Kaarene Fitzgerald PhD scholarship to pursue research into the underlying mechanisms of SIDS at The Ritchie Centre, Department of Paediatrics, Monash University in Melbourne. She started her doctoral research in 2014, investigating the effects of intra-uterine growth restriction (IUGR) on the brain and the heart in newborns and infants born preterm.

Dr Emily Cohen
Dr Emily Cohen

Intra-uterine growth restriction (IUGR) is when a baby is born too small for the duration of the pregnancy. It significantly increases the risk of Sudden Unexpected Death in Infancy (SUDI) and has also been linked to poorer neurodevelopmental outcome in childhood and cardiovascular disease in adulthood. However, the underlying mechanisms for these increased risks have not been elucidated.

IUGR often results from a poorly functioning placenta, which compromises the delivery of oxygen and nutrients to the developing fetus. Under these challenging conditions, the fetus adapts its blood flow to preserve oxygen and nutrient supply to the brain and heart. Although these changes are protective during pregnancy, they may cause permanent changes within the heart, brain and blood vessels, which could potentially explain the increased risk for SUDI and poor long-term outcomes.

Over the three years of her PhD Emily followed a total of 67 IUGR and appropriately grown infants throughout the first few months of life. She investigated a variety of parameters that define cardiovascular function, such as heart function using echocardiography and heart rate control. She also analysed existing data from The Netherlands on brain oxygenation and brain blood flow in IUGR and appropriately grown newborns.

Her results suggest that IUGR newborns display changes in the shape of the heart, which may make them prone to unstable blood pressure, that they have altered brain oxygenation and brain blood flow, and that they seem more vulnerable to unstable brain perfusion. These findings highlight that preterm IUGR newborns are a fragile group within the neonatal intensive care unit. Emily’s studies highlight that they may benefit from tailored monitoring and management strategies to improve their health outcomes.

Some of the early changes in heart shape and function appeared to persist well into infancy. Alterations in infant brain maturation were also noted. These changes were mainly observed during early infancy, when the risk of SIDS is the greatest. Although an improvement over time was seen, altered early brain and heart development may also contribute to poorer long-term neurodevelopmental and cardiovascular outcomes in infants born preterm and IUGR.

So far this study has produced 4 research papers for publication and the results have been presented at various national and international conferences. Emily also presented her results at the 2016 Kaarene Fitzgerald meeting and was invited to discuss her research on Triple R.

In May this year Emily returned to the Netherlands to pursue a career as a paediatrician. She will defend her PhD entitled “From head to heart; the effects of IUGR and preterm birth on the cerebral and systemic circulation” at Utrecht University on the 12th of October.


COHEN E, WONG FY, HORNE RSC, YIALLOUROU SR. Intrauterine growth restriction: impact on cardiovascular development and function throughout infancy. Pediatric Research 79(6):821-30, 2016.

COHEN E, WONG FY, WALLACE EM, MOCKLER JC, ODOI A, HOLLIS S, HORNE RSC, YIALLOUROU SR. Fetal growth restriction alters autonomic cardiovascular control in the immediate postnatal period but not during infancy. Pediatric Research, May 3. doi: 10.1038/pr.2017.105. [Epub ahead of print] 2017.

COHEN E, WHATLEY C, WONG FY, WALLACE EM, MOCKLER JC, ODOI A, HOLLIS S, HORNE RSC, YIALLOUROU SR. Effect of fetal growth restriction and preterm birth on cardiac structure and function in infancy. Submitted to Archives Disease in Childhood April 2017.

COHEN E, WONG FY, WALLACE EM, MOCKLER JC, ODOI A, HOLLIS S, HORNE RSC, YIALLOUROU SR. EEG power spectrum maturation in preterm fetal growth restricted infants. Submitted to Brain Research May 2017.