Stillbirths and neonatal deaths

Australia is one of the safest places in the world for a baby to be born, yet death occurring within the perinatal period (from 20 weeks of gestation to 28 days after birth) is not uncommon. Every day in Australia, 6 babies are stillborn and 2 die within 28 days of birth (neonatal death).

In 2019, there were:

• 303,054 babies born to 298,567 women
• 2,897 perinatal deaths (less than 1% of babies born). Of these deaths, just over 75% were stillbirths (2,183) and 25% (714) were neonatal deaths
• 9.6 perinatal deaths per 1,000 births (7.2 stillbirths per 1,000 births and 2.4 neonatal deaths per 1,000 live births).

Although perinatal mortality rates have remained relatively unchanged since 2000, two categories have decreased over the period:

• neonatal deaths of babies born at 23 weeks’ gestation or more
• stillbirths occurring at 28 weeks’ gestation or more.

International comparison using the WHO definition

The WHO definition of stillbirth results in reporting of babies who are larger and more mature than the definition applied in Australia. This means Australian perinatal mortality rates reported using the WHO definitions are lower than those reported using Australian definitions.

Using the WHO definitions (stillbirths from the third trimester and all neonatal deaths):

• The rate of stillbirths in Australia has decreased from 3.8 per 1,000 births in 2000 to 2.6 per 1,000 births in 2019.
• The rate of neonatal deaths in Australia is the same using both Australian and WHO definitions, and has decreased from 2.9 per 1,000 live births in 2000 to 2.4 per 1,000 live births in 2019.

References

• WHO 2018. Global reference list of 100 core health indicators, 2018.

Key demographics

In 2019, there were:

• 9.6 perinatal deaths per 1,000 births (2,897 deaths)
• 7.2 stillbirths per 1,000 births (2,183 deaths)
• 2.4 neonatal deaths per 1,000 live births (714 deaths).

Perinatal mortality rates were higher among babies born to:

• women who were aged under 20, 20-24 and 40 and over (18.4, 11.1, and 15.1 deaths per 1,000 births, respectively)
• Aboriginal and Torres Strait Islander women (14.8 deaths per 1,000 births)
• women who lived in Very remote areas (19.6 deaths per 1,000 births)
• women living in the most disadvantaged areas of Australia (quintiles 1 and 2; 11.1, and 9.8 deaths per 1,000 births, respectively).

Detailed data can be found in TAB3 of the supplementary data tables

Country of birth

There was little overall difference in perinatal mortality rates for babies of women born in Australia compared to babies of women born overseas. The highest rates of perinatal death were among babies of women whose country of birth was in:

• North Africa
• Polynesia (excludes Hawaii)
• Melanesia.

Detailed country of birth data can be found in TAB3 of the supplementary data tables.

Gestational age and birthweight

A baby may be small due to being pre-term (born early), or due to being small for gestational age (either because it is small due to genetic factors, or because it is the subject of a growth restriction within the uterus). Poor fetal growth is associated with increased risk of perinatal death and with fetal distress during labour, and these babies are more likely to develop long-term health conditions later in life.

Adjusting birthweight for gestational age allows for differences in a baby’s growth status and maturity to be taken into account when examining their health outcomes at birth.

Babies are defined as being small for gestational age if their birthweight is below the 10th percentile for their gestational age and sex, as determined by national percentiles. Babies are defined as large for gestational age if their birthweight is above the 90th percentile for their gestational age and sex.

In 2019:

• Nearly 2 in 5 perinatal deaths (38.9%) occurred before 22 completed weeks’ gestation
• Rates of perinatal death decreased rapidly from 28 weeks’ gestation and were lowest among babies born at term (37-41 weeks).

The highest rates of perinatal death were among:

• Babies born at less than 22 weeks’ gestation (998.2 deaths per 1,000 births)
• Babies born in the second trimester (less than 28 weeks’ gestation; 691.8 deaths per 1,000 births)
• Babies born with a birthweight less than 2,500 grams (108.8 deaths per 1,000 births)
• Babies who were small for gestational age (birthweight below the 10^th percentile for their age and sex; 23.4 deaths per 1,000 births)
• Multiple births (32.0 deaths per 1,000 births).

Detailed data can be found in TAB4 of the supplementary data tables

Gestational age trend

While perinatal mortality rates have been holding relatively steady for babies born before 28 weeks’ gestation, they have been gradually decreasing among babies born after 28 weeks’ gestation.

Stillbirths occurring after 28 weeks of gestation, or in the third trimester of pregnancy, are known as late gestation stillbirths. Evidence indicates that these stillbirths are the most likely to be preventable (Flenady et al. 2016). The rate of late gestation stillbirths in Australia has decreased from 3.7 per 1,000 births in 2000 to 2.5 per 1,000 births in 2019.

Neonatal deaths in both the second and third trimesters of pregnancy have decreased over this period, with deaths in the third trimester decreasing from 1.2 per 1,000 births to 0.8 per 1,000 births in 2019.

References

Flenady, V., Wojcieszek, A.M., Middleton, P., Ellwood, D., Erwich, J.J., Coory, M., Khong, T.Y., Silver, R.M., Smith, G.C., Boyle, F.M. and Lawn, J.E (2016) ‘Stillbirths: recall to action in high-income countries’. The Lancet, 387:691-702, doi:10.1016/S0140-6736(15)01020-X

Timing of perinatal deaths

In 2019, where the timing of perinatal deaths was stated:

• Nearly three in five (59.6%) perinatal deaths and the majority (82.7%) of stillbirths occurred before the onset of labour (antepartum death)
• Three in five (60.4%) neonatal deaths occurred within the first 24 hours following birth (very early neonatal death) and were more common with decreasing gestational age
• Early neonatal deaths (1–7 days) (38.9%) and late neonatal deaths (8–28 days) (42.1%) were more common among babies born from 36 weeks’ gestation.

Detailed data can be found in TAB6 of the supplementary data tables.

Causes of perinatal death

Causes of perinatal deaths are classified according to the Perinatal Society of Australia and New Zealand (PSANZ) Perinatal Mortality Classification System, version 3.2, as part of each state or territory’s perinatal mortality review process.

The PSANZ Perinatal Mortality Classification System incorporates a Perinatal Death Classification (PSANZ-PDC) and an additional Neonatal Death Classification (PSANZ-NDC).

The PSANZ-PDC system classifies all perinatal deaths (stillbirths and neonatal deaths) by the single most important factor which led to the chain of events that resulted in the death (refer to Technical notes—Definitions used in reporting for cause of death classifications).

In 2019:

The most commonly classified causes for all perinatal deaths were:

• Congenital anomaly (31.7%)
• Spontaneous preterm birth (13.6%)
• Unexplained antepartum death (11.5%).

The most commonly classified causes of stillbirths were:

• Congenital anomaly (31.3%)
• Unexplained antepartum death (15.3%)
• Maternal conditions (13.0%).

The most commonly classified causes of neonatal deaths were:

• Congenital anomaly (32.8%)
• Spontaneous preterm birth (29.0%)
• Antepartum haemorrhage (10.4%).

In 2019, congenital anomaly was the most commonly classified cause of perinatal death. This remained true across almost all deaths, regardless of maternal or gestational age, plurality, baby’s birthweight percentile or the timing of death. The only exceptions to this were for:

• Late gestation stillbirths. Unexplained antepartum death was the most commonly classified cause of death for stillbirths occurring at 32-35 and 36+ weeks’ gestation (25.0% and 26.8%, respectively).
• Early gestation neonatal deaths. Spontaneous preterm birth was the most commonly classified cause for neonatal deaths occurring at 20-22 and 23-26 weeks’ gestation (both 42.9%).
• Babies born to mothers aged under 20. Maternal conditions were the most commonly classified cause of perinatal death for babies born to mothers aged under 20 (30.4%). Maternal conditions refers to deaths where a medical condition (e.g. diabetes) or a surgical condition (e.g. appendicitis) or an injury in the mother (including complications or treatment of that condition) is the cause.
• Multiple births. Complications of multiple pregnancy was the most commonly classified cause for multiples (37.3%), followed by spontaneous preterm birth (21.1%).
• Neonatal deaths in babies considered appropriate for gestational age (AGA). Spontaneous preterm birth was the main classified cause of neonatal deaths for babies considered appropriate birthweight for their gestational age (34.4%).

Causes of neonatal deaths

The PSANZ-NDC is an additional classification system applied only to neonatal deaths to identify the single most significant condition present in the neonatal period that caused the baby’s death.

In 2019, the most commonly classified conditions causing neonatal deaths were:

• Periviable infants (infants deemed too immature for resuscitation or continued life support; 35.9%)
• Congenital anomaly (30.5%)
• Neurological conditions (13.4%).

Investigation following perinatal death

Autopsy

References

RCOG (Royal College of Obstetricians and Gynaecologists) (2010) Late Intrauterine Fetal Death and Stillbirth: Green top guideline No.55, RCOG, accessed 7 October 2021.