Small babies among births at or after 40 weeks gestation

Clinical commentary

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 (AIHW 2016).

Babies born at or after 40 completed weeks of gestational age (280 or more days after the first day of the last menstrual period) with a birthweight less than 2,750 grams are likely to have been affected by intrauterine growth restriction (IUGR) (AIHW 2016). Poor fetal growth is associated with increased risks of fetal death and compromise in labour, late fetal growth restriction may predispose the baby to hypertension and diabetes in adulthood (Draper et al. 2017; Flenady et al. 2018; Sharma et al. 2016).

Some babies whose intrauterine growth is normal are small, and female babies are normally smaller than male babies of the same gestational age. Use of sex-specific birthweight cut-off points would align this indicator more closely with growth restriction.


For this indicator, small babies at or after 40 weeks gestation is defined at birthweight less than 2,750 grams; the definition of low birthweight (grams) may be different in other national or international reporting indicators. 

Indicator specifications and data

Excel source data tables are available from the Data tab.

For more information refer to Specifications and notes for analysis in the technical notes.


  • AIHW (Australian Institute of Health and Welfare) 2016. Australia’s health 2016. Australia’s health series no. 15. Cat. no. AUS 199. Canberra: AIHW.
  • Draper ES, Kurinczuk JJ & Kenyon S 2017. MBRRACE-UK 2017 Perinatal Confidential Enquiry: Term, singleton, intrapartum stillbirth and intrapartum-related neonatal death. The Infant Mortality and Morbidity Studies. Leicester: Department of Health Sciences.

  • Flenady V, Wojiezek AM & Middleton P 2018. Stillbirths: recall to action in high-income countries. Lancet 387(10019):691–702.
  • Sharma D, Shastri S & Sharma P 2016. Intrauterine growth restriction: antenatal and postnatal aspects. Clinical Medicine Insights: Pediatrics 10:67–83.