Fetal growth restriction (FGR)

FGR, sometimes also called intrauterine growth restriction (IUGR), is a common pregnancy complication where an unborn baby is smaller than expected for their stage of pregnancy. More than one in seven Australian babies, around 20,000 each year are born growth-restricted.

FGR can put babies at risk of heart, lung and brain injury and life-long problems like hypertension, cerebral palsy, autism, learning and other behavioural dysfunctions. FGR is also the leading cause of stillbirth, increasing that risk up to 20-fold.

Causes, types and risks: How scientists are helping

Types of FGR

There are two main forms of FGR

Symmetrical FGR – all parts of the body are a similar small size.
Asymmetrical FGR – the head and brain are a normal size, but the rest of the body is small.

FGR can begin at any time during pregnancy, and the effects depend on how early and how severely growth is restricted.

What causes FGR?

The most common cause of FGR is a problem with the placenta – the organ that delivers nutrients and oxygen to the developing baby during pregnancy.

When the placenta doesn’t work properly, the baby receives less oxygen and fewer nutrients, leading to slower growth. Reduced oxygen can cause inflammation and cell damage (known as oxidative stress), which may harm the developing brain before birth.

Risk factors for FGR

The largest risk factor – placental insufficiency – cannot be prevented. However, certain maternal factors can increase the likelihood of FGR, including

Maternal obesity
Having a previous pregnancy affected b FGR
Smoking, drinking alcohol or using illegal drugs
Some medicines
Having an existing medical condition eg; high blood pressure, heart disease, diabetes
Carrying multiples eg; twins, triplets
Conceiving within 18 months of a previous birth
Having previously had a small baby or stillbirth
Being under 17 or over 35 years of age
Having pregnancy complications eg; preeclampsia, heavy bleeding.

Uterine/placental factors can also lead to FGR, such as

Decreased blood flow in the uterus and placenta
Detachment of the placenta from the uterus
The placenta attaching too low in the uterus
Infection in tissues around the fetus.

Reducing risk

While some risk factors can’t be changed, others can be managed. Pregnant women can help lower the risk of FGR by

Quitting smoking and avoiding drugs and alcohol
Eating a healthy balanced diet
Maintaining a healthy weight before and during pregnancy

Regular prenatal care and early detection are vital for improving outcomes.

How our researchers are helping with Fetal growth restriction (FGR)

Researchers at Hudson Institute of Medical Research are investigating how placental dysfunction causes FGR and developing new ways to detect and treat it. Their work aims to protect vulnerable babies from brain, heart and lung injury and to reduce lifelong complications arising from FGR – helping give every baby the best possible start to life.

Improving the transition at birth in newborns with growth restriction.

Dr Beth Allison’s project aims to determine the cardiovascular adaptations that a growth restricted fetus takes to survive chronic hypoxia, and how this alters the cardiovascular transition at birth, making the newborn prone to cardiovascular disease and brain injury. The team also aim to identify strategies to improve cardiovascular function in growth restricted newborns.

Team | Dr Beth Allison, Professor Suzie Miller

Improving functional deficits associated with fetal growth restriction

New treatment. Professor Suzanne Miller’s project is examining treatment strategies that will help improve the structure and function of the developing brain.

Several different neuroprotective strategies are under investigation that could be used during pregnancy (antenatally) or after birth (postnatally) that aim to optimise a developing baby’s brain development. The treatments include antioxidants, anti-inflammatory compounds and cord blood stem cells.

Team | Professor Suzanne Miller, Dr Beth Allison, Dr Emily Camm

Investigating the effect of birth asphyxia in growth restricted newborns.

The aim of this project is to develop strategies to protect the growth restricted newborn from the consequences of perinatal asphyxia – a common comorbidity.

The team is investigating the unique physiological response to perinatal asphyxia and developing potential treatments, including beta blockers and physiological-based cord clamping, to reduce morbidities associated with perinatal asphyxia in growth restricted newborns.

Team | Dr Beth Allison, Professor Graeme Polglase

Early diagnosis of brain injury associated with FGR

Early detection. Imaging. Professor Suzanne Miller and A/Professor Atul Malhotra are using advanced imaging techniques such as magnetic resonance imaging (MRI) scans to detect subtle brain injury associated with FGR. A/Prof Malhotra is a consultant neonatologist at Monash Children’s Hospital and an Honorary Clinical Associate at Hudson Institute’s Ritchie Centre.

In preclinical research, Prof Miller and A/Prof Malhotra have shown that advanced MRI techniques can detect altered brain organisation in the FGR brain. The team are now translating this into early detection of subtle brain changes in human infants.

Team | Professor Suzanne Miller, Associate Professor Atul Malhotra

Assessing antenatal maternal melatonin supplementation for fetal neuroprotection in early-onset FGR

Clinical trial protocol. Melatonin is a powerful antioxidant that can reduce oxidative stress. In a clinical trial pregnant women with a growth restricted fetus are taking melatonin to determine if it can protect at-risk babies’ developing brains. Read more about the ProtectMe clinical trial.

Professor Suzanne Miller is working with collaborators in the trial including Dr Kirsten Palmer, Monash Health along with hospitals across Australia and New Zealand.

Lead Researcher | Professor Suzanne Miller

The effects of FGR on the developing preterm lung and cardiovascular system

Dr Beth Allison and Professor Suzanne Miller are investigating the effect of FGR and brain-sparing on cardiovascular system development.

The project goal is to identify the mechanisms that alter organ development in utero, particularly brain-sparing adaptations, and how these can predict postnatal pathological outcomes.

Dr Allison and the team are working to understand better ways to predict long term outcomes in FGR, to ensure that FGR is detected and treated, allowing vulnerable babies to have the healthiest start to life possible.

Team | Dr Beth Allison, Professor Suzanne Miller