Babies weighing less than the third centile
Birthweight is a key indicator of infant health that is used both as an outcome measure for health and wellbeing of the mother in pregnancy and a principal determinant of a baby’s chance of prospective survival, good health, development and wellbeing (WHO 2022b). Adjusting birthweight for gestational age allows for differences in a baby’s growth status and maturity to be considered when examining their health at birth. Severe fetal growth restriction (FGR) is defined as those babies born with a birthweight less than the third centile for gestational age and sex (Safer Care Victoria 2024). For more information, see Clinical commentary.
This indicator has two parts. The first part examines the proportion of babies who are identified as having severe FGR amongst all babies born at or after 40 weeks gestation. The second part examines the proportion of babies with severe FGR who are born at or after 40 weeks gestation.
Key findings
In 2023, 2.1% of babies born at or after 40 weeks gestation had severe FGR.
This proportion:
- decreased from 3.4% in 2004 to 2.1% in 2023
- was higher for babies born to mothers who reported smoking during pregnancy compared with mothers who did not (4.2% compared with 2.0% in 2023).
In 2023, around 1 in 5 (23%) babies with severe FGR were born at or after 40 weeks gestation.
This proportion:
- nearly halved from 44% in 2004 to 23% in 2023
- was slightly higher for public hospitals than private hospitals (23% compared with 19% in 2023).
The interactive data visualisation (Figure 14) presents data on babies with severe FGR. Use the drop-down menus to view data by selected characteristics and the latest year button to explore data for 2023.
Figure 14: Babies weighing less than the third centile
This data visualisation presents data on babies with severe FGR. Interactive charts show proportions for the most recent data and over time, for selected demographic and birth characteristics.
Clinical commentary
A low birthweight for gestational age indicates a possible fetal growth restriction within the uterus. Poor fetal growth is associated with increased risk of stillbirth and with fetal distress during labour, and may make babies more likely to develop long-term health conditions later in life (AIHW 2025). Poor fetal growth is associated with increased risks of fetal death and compromise in labour (Draper et al. 2017). Late fetal growth restriction may predispose the baby to hypertension and diabetes in adulthood (Flenady et al. 2018; Sharma et al. 2016).
The timely identification of a growth restricted fetus allows for comprehensive monitoring and consultation with the parents regarding the most appropriate delivery time to optimise short-term and longer-term outcomes. Very small babies are usually born as a planned birth (through induction of labour or pre-labour caesarean section) (Safer Care Victoria 2024) with the aim of achieving the maximum maturity possible while balancing the risks of continuing the pregnancy for both the mother and the fetus (Stillbirth CRE 2023).
Birth after 40 weeks gestation suggests that the growth restriction may not have been detected and managed in a timely way (Safer Care Victoria 2024). The risk of perinatal death increases after 37 weeks in small fetuses and newborns, and while the exact timing will depend on a range of factors, clinical guidelines consistently recommend delivery occur before 40 weeks gestation (Francis et al. 2014; Lausman and Kingdom 2021; RCOG 2024; Safer Care Victoria 2024; Stillbirth CRE 2023).
Indicator specifications and data
Excel source data tables are available from Data.
For more information, refer to Data specifications and Methods.
AIHW (2025) Australia’s mothers and babies, AIHW, Australian Government, accessed 18 August 2025.
Draper ES, Kurinczuk JJ and Kenyon S (2017) Perinatal Confidential Enquiry: Term, singleton, intrapartum stillbirth and intrapartum-related neonatal death, MBRRACE-UK, Healthcare Quality Improvement Partnership, accessed 6 June 2023.
Francis JH, Permezel M and Davey MA (2014) ‘Perinatal mortality by birthweight centile’, Australian and New Zealand Journal of Obstetrics and Gynaecology, 54(4):354–359, doi:10.1111/ajo.12205.
Flenady V, Wojiezek AM and Middleton P (2018) ‘Stillbirths: recall to action in high-income countries’, Lancet, 387(10019):691–702, doi:10.1016/S0140-6736(15)01020-X.
Lausman A and Kingdom J (2021) ‘How and when to recommend delivery of a growth-restricted fetus: A review’, Best Practice & Research Clinical Obstetrics & Gynaecology, 77:119–128, doi:10.1016/j.bpobgyn.2021.09.006.
RCOG (Royal College of Obstetricians and Gynaecologists) (2024) Investigation and Care of a Small-for-Gestational-Age Fetus and a Growth Restricted Fetus (Green-top Guideline No. 31), RCOG, accessed 15 September 2025.
Safer Care Victoria (2024) Victorian perinatal services performance indicators 2021, Safer Care Victoria, Victorian Government, accessed 17 July 2024.
Sharma D, Shastri S and Sharma P (2016) ‘Intrauterine growth restriction: antenatal and postnatal aspects’, Clinical Medicine Insights: Pediatrics, 10:67–83, doi:10.4137/CMPed.S40070.
Stillbirth Centre of Research Excellence (Stillbirth CRE) (2023) Fetal growth restriction position statement, Stillbirth CRE, accessed 17 July 2024.
WHO (2022b) ‘WHO recommendations for care of the preterm or low-birth-weight infant’, WHO, accessed 26 June 2025.