Focus group: Near-term singleton perinatal deaths without congenital anomaly
In order to present detailed and robust statistics for this focus group, data for 2 years – 2020 and 2021 – are combined.
This section examines perinatal deaths that occurred in singleton pregnancies, where the baby did not have a major congenital anomaly causing death and where the pregnancy ended at or after 36 weeks of gestation. For the purposes of this report, such babies are called ‘near-term normally-formed singleton babies’.
These babies have the lowest incidence of known risk factors for perinatal death, and so any deaths occurring in this group of babies are considered to be unexpected. When considering prevention of perinatal deaths, review of perinatal deaths in this group of babies is likely to provide insights to inform policy and practice in maternity and neonatal care (Draper et al. 2015, 2017; RCOG 2017).
A near-term normally-formed singleton baby is one that meets all 3 of the following criteria:
- Born at or after 36 weeks of gestation
- Plurality that of a singleton fetus
- Cause of death not due to a congenital anomaly
Mortality rates are calculated relative to the number of births that meet the first two criteria.
In 2020–2021, near-term normally-formed singleton babies accounted for a large proportion (571,160, 93%) of all babies born and a small proportion (720, 12%) of perinatal deaths. Perinatal deaths among this group:
- occurred at a low rate compared with all babies born in Australia, with 1.3 deaths per 1,000 births in 2020–2021 compared with 9.8 deaths per 1,000 births among all babies in 2020–2021
- were more commonly a stillbirth (563, 78%) than a neonatal death (157, 22%)
- occurred at the highest rate at 36 weeks of gestation (7.5 perinatal deaths per 1,000 births) and among babies with a birthweight less than the 10th percentile (2.6 perinatal deaths per 1,000 births).
Trends in perinatal mortality rates
Trends in this section cover the period from 2013 onwards as data on cause of death are missing from some states and territories prior to 2013.
The rate of perinatal death among near-term normally-formed singleton babies has remained relatively unchanged since 2013, varying between 1.2 and 1.5 deaths per 1,000 births (Figure 1).
Figure 1: Perinatal mortality rates among near-term normally-formed singleton babies, 2013–2021
Rates of stillbirth, neonatal death, and overall perinatal death between 2005 and 2021 among near-term singleton babies without congenital anomaly.
Year | Perinatal deaths | Stillbirths | Neonatal deaths |
---|---|---|---|
2013 | 1.4 per 1,000 births | 1.2 per 1,000 births | 0.3 per 1,000 births |
2014 | 1.5 per 1,000 births | 1.2 per 1,000 births | 0.3 per 1,000 births |
2015 | 1.4 per 1,000 births | 1.2 per 1,000 births | 0.2 per 1,000 births |
2016 | 1.2 per 1,000 births | 1 per 1,000 births | 0.3 per 1,000 births |
2017 | 1.5 per 1,000 births | 1.2 per 1,000 births | 0.3 per 1,000 births |
2018 | 1.2 per 1,000 births | 0.9 per 1,000 births | 0.3 per 1,000 births |
2019 | 1.2 per 1,000 births | 1 per 1,000 births | 0.3 per 1,000 births |
2020 | 1.2 per 1,000 births | 0.9 per 1,000 births | 0.3 per 1,000 births |
2021 | 1.3 per 1,000 births | 1 per 1,000 births | 0.2 per 1,000 births |
Notes:
- The rate is the number of deaths per 1,000 births. Stillbirth and perinatal mortality rates were calculated using total births (live births and stillbirths). Neonatal mortality rates were calculated using live births.
Source:
AIHW analysis of the National Perinatal Mortality Data Collection and the National Perinatal Data Collection
|
Data source overview
Maternal characteristics
This section presents data on the mother’s demographic and medical characteristics that have been commonly associated with stillbirth or neonatal death of near-term normally-formed singleton babies.
While these characteristics are more commonly found in women with pregnancies that result in stillbirth and neonatal death, it is not implied that these characteristics are the cause of perinatal death.
The overall rate of perinatal mortality among near-term normally-formed singleton babies in 2020–2021 was 1.3 deaths per 1,000 births. Perinatal mortality rates were higher among babies born to:
- women with pre-existing diabetes mellitus (5.4 deaths per 1,000 births)
- women who accessed 2 or fewer antenatal visits (4.4 perinatal deaths per 1,000 births)
- women who were aged under 20 (2.9 deaths per 1,000 births)
- women who have had four or more previous births (2.8 deaths per 1,000 births)
- women who reported smoking throughout pregnancy (2.7 deaths per 1,000 births)
- women living in the most disadvantaged areas of Australia (1.7 deaths per 1,000 births for SEIFA quintile 1)
- women who lived in Remote and very remote areas (1.7 deaths per 1,000 births)
- women classed as obese (BMI of 30 or more; 1.6 deaths per 1,000 births).
Many of these associations are also observed for all perinatal deaths in Australia (see Stillbirths and neonatal deaths: Maternal characteristics for more details).
Detailed data on perinatal mortality rates by selected maternal characteristics can be explored in the interactive data visualisation below (Figure 2), with data also presented in Table 16 of the supplementary data tables (Data tables: National Perinatal Mortality Data Collection annual update 2021).
Figure 2: Perinatal mortality rates among near-term normally-formed singleton babies, by selected maternal characteristic, 2020–2021
Rates of perinatal death for near-term normally-formed singleton babies in 2020-2021 by various maternal demographic characteristics, mother's age.
![](https://viz.aihw.gov.au:443/t/Public/views/PER101_sandia_tsnf_year_maternal_characteristics_30072024/dash_plot.png?:embed=y&:showVizHome=no&:display_spinner=no&:host_url=https%3a%2f%2fviz.aihw.gov.au)
Baby characteristics
This section presents data on characteristics of near-term normally formed babies where perinatal death occurred. These characteristics include gestational age (the duration of the pregnancy in completed weeks), birthweight, and birthweight for gestational age.
The length of pregnancy and the weight of the baby are often related. Using birthweight for gestational age allows for differences in a baby's growth and maturity to be considered in relation to health outcomes. For example, a baby may be small because it has been born early, or it may be small for its gestational age when compared with other babies of the same age. It might be small due to genetic factors, or because of a growth restriction within the uterus. Babies are considered small for gestational age when their birthweight is below the 10th percentile for their gestational age and sex.
In 2020–2021, the overall rate of perinatal deaths in near-term normally formed babies was 1.3 deaths per 1,000 births. Perinatal mortality rates were highest for:
- babies born at 36 weeks’ gestation (7.5 deaths per 1,000 births)
- babies born with a birthweight less than 2,500 grams (5.6 deaths per 1,000 births)
- babies who were small for gestational age (2.6 deaths per 1,000 births), especially for those babies whose birthweight was less than the 3rd percentile for their gestational age (4.0 deaths per 1,000 births).
Detailed data on perinatal mortality rates by birthweight, gestational age and sex can be explored in the interactive data visualisation below (Figure 3), with data also presented in Table 17 of the supplementary data tables (Data tables: National Perinatal Mortality Data Collection annual update 2021).
Figure 3: Perinatal mortality rates among near-term normally-formed singleton babies, by selected baby characteristic, 2020–2021
Rates of perinatal death in 2020-2021 by characteristics of the baby and pregnancy for near-term normally-formed singleton babies, including birthweight and gestational age.
![](https://viz.aihw.gov.au:443/t/Public/views/PER101_sandia_tsnf_year_baby_characteristics_30072024/dash_plot.png?:embed=y&:showVizHome=no&:display_spinner=no&:host_url=https%3a%2f%2fviz.aihw.gov.au)
Timing of perinatal death
Among near-term normally-formed singleton babies, nearly three-quarters (72%) of perinatal deaths occurred prior to the onset of labour (antepartum stillbirth) (Figure 4).
Figure 4: Number of perinatal deaths among near-term normally formed singleton babies, by timing of death, 2020–2021
Number of perinatal deaths in 2020-2021 among near-term singleton babies born without congenital anomaly, by timing of death. Antepartum deaths were most common, accounting for 476 perinatal deaths.
Timing of perinatal death | Number of perinatal deaths |
---|---|
Antepartum | 476 |
Intrapartum | 29 |
Very early neonatal (less than 1 day) | 38 |
Early neonatal (1–7 days) | 71 |
Late neonatal (8–28 days) | 48 |
Source:
AIHW analysis of the National Perinatal Mortality Data Collection
|
Data source overview
Causes of death
Classifying cause of death
Causes of perinatal deaths are classified according to the Perinatal Society of Australia and New Zealand (PSANZ) Perinatal Mortality Classification System, version 3.0, as part of each state or territory’s perinatal mortality review process. This system is a way of grouping the causes of perinatal death to better understand and prevent them in the future.
The PSANZ Perinatal Mortality Classification System has two different classifications. The first is the Perinatal Death Classification (PSANZ-PDC), which includes maternal and fetal causes and is applied to all perinatal deaths (stillbirths and neonatal deaths). The second is the Neonatal Death Classification (PSANZ-NDC), which includes neonatal causes and is applied to neonatal deaths only. It is used in addition to the Perinatal Death Classification.
Refer to Technical notes – Definitions for more information on cause of death classifications.
The most common causes of perinatal death for near-term normally-formed singleton babies, using the PSANZ-PDC classification, were stillbirths where no cause could be found (‘unexplained antepartum death’) (22%) and deaths where the placenta wasn’t functioning well (‘placental dysfunction or causative placental pathology’) (17%) (Figure 5).
The most common causes of stillbirth and neonatal death were different from each other. For stillbirths, the most common cause was ‘unexplained antepartum death’ (29%), followed by ‘placental dysfunction or causative placental pathology’ (20%).
For neonatal deaths, the most common cause was not receiving enough oxygen from the placenta (‘hypoxic peripartum death’, 38%), followed by deaths which could not be explained by a problem in the pregnancy (‘neonatal death without obstetric antecedent’, 22%).
Causes of perinatal deaths among near-term normally-formed singleton babies also varied by birthweight percentile. Deaths among babies considered small for their gestational age (weighing less than the 10th percentile), which accounted for 134 or 19% of perinatal deaths, were most commonly due to ‘placental dysfunction or causative placental pathology’ (38 perinatal deaths), followed by ‘unexplained antepartum death’ (28 perinatal deaths).
Babies considered large for their gestational age (weighing greater than the 90th percentile) most commonly died as a result of ‘unexplained antepartum death’ (18 perinatal deaths), followed by ‘maternal conditions’ (16 perinatal deaths), which includes medical conditions (for example, diabetes), surgical conditions (for example, appendicitis) and injuries, as well as complications or treatment of that condition.
Figure 5: Number of perinatal deaths among near-term normally formed singleton babies, by PSANZ Perinatal Death Classification, 2020–2021
Number of perinatal deaths in 2020-2021 among near-term singleton babies born without congenital anomaly, by PSANZ Perinatal Death Classification. Unexplained antepartum fetal death was the most commonly classified cause, with 161 deaths.
PSANZ Perinatal Death Classification | Number of perinatal deaths |
---|---|
Unexplained antepartum fetal death | 161 |
Placental dysfunction | 121 |
Hypoxic peripartum death | 92 |
Specific perinatal conditions | 82 |
Antepartum haemorrhage | 75 |
Perinatal infection | 52 |
Maternal conditions | 41 |
Not stated | 41 |
Neonatal death without obstetric antecedent | 34 |
Hypertension | 18 |
Spontaneous preterm | 3 |
The category of unexplained antepartum fetal death includes deaths of normally-formed fetuses prior to the onset of labour where no identified predisposing factors are considered likely to have caused the death, as well as deaths where insufficient information was available to allow more specific classification of the cause of death.
Source:
AIHW analysis of the National Perinatal Mortality Data Collection
|
Data source overview
The PSANZ-NDC classification system is applied only to neonatal deaths, to identify the single most significant condition present in the neonatal period that caused the baby’s death. For the majority of neonatal deaths among near-term normally-formed singleton babies, the single most significant condition that caused the baby’s death was brain damage due to oxygen deprivation or bleeding in the brain (‘neurological conditions’, 54%) (Figure 6).
Figure 6: Number of neonatal deaths among near-term normally formed singleton babies, by PSANZ Neonatal Death Classification, 2020–2021
Number of neonatal deaths in 2020-2021 among near-term singleton babies born without congenital anomaly, by PSANZ Neonatal Death Classification. Neurological conditions was the most commonly classified cause, with 84 neonatal deaths.
PSANZ Neonatal Death Classification | Number of neonatal deaths |
---|---|
Neurological | 84 |
Other | 37 |
Not stated | 15 |
Cardio-respiratory disorders | 10 |
Neonatal infection | 8 |
Gastrointestinal | 2 |
Periviable infants | 1 |
Source:
AIHW analysis of the National Perinatal Mortality Data Collection
|
Data source overview
Detailed data on the causes of perinatal deaths among near-term normally-formed singleton babies in 2020–2021 is presented in Table 18 of the supplementary data tables (Data tables: National Perinatal Mortality Data Collection annual update 2021).
Autopsy following perinatal death
This section presents data on autopsy, identified by PSANZ as a core investigation (test) to be undertaken following all perinatal deaths (Flenady et al. 2020).
The purpose of an autopsy is to accurately identify the cause(s) of death. Autopsy results contribute to clinical audit and assist with identification of factors contributing to the death, and may be critical when clinicians consider providing parents with advice regarding the risk of a future perinatal death (RCOG 2010). Perinatal autopsy examinations require written consent from the parent(s) following informed discussion.
Testing such as autopsy is of particular importance in seeking the underlying causes of death in near-term normally-formed singleton babies. A greater proportion of these babies have causes of death that are unknown (‘unexplained antepartum death’), not well understood (‘hypoxic peripartum death’), or cannot be explained by a problem occurring in the pregnancy (‘neonatal death without obstetric antecedent’). Combined, these 3 causes of death accounted for 40% of deaths in near-term normally-formed singleton babies. This is a higher incidence than for all perinatal deaths, where these causes of death accounted for 14% of deaths.
Where autopsy status was known, autopsy was performed more frequently among near-term normally-formed singleton babies (57%) than for perinatal deaths occurring across all babies (41%). For near-term normally-formed singleton babies, the proportion of autopsy was similar across stillbirths (57% of stillbirths) and neonatal deaths (59% of neonatal deaths).
The frequency at which autopsy was conducted varied by timing of perinatal death, with the highest proportion being performed in very early (less than 24 hours) neonatal deaths (72%).
The frequency of autopsy also varied by cause of death, with 77% of neonatal deaths with ‘no obstetric antecedent’ undergoing an autopsy compared with 30% of deaths due to ‘antepartum haemorrhage’. Autopsy investigation was conducted in less than half of stillbirths classified as ‘unexplained antepartum deaths’ (47%).
Detailed data on the investigation of perinatal deaths among near-term normally-formed singleton babies in 2020–2021 can be explored in the interactive data visualisation below (Figure 7), with data also presented in Table 18 of the supplementary data tables (Data tables: National Perinatal Mortality Data Collection annual update 2021).
Figure 7: Proportion of perinatal deaths among near-term normally-formed singleton babies where autopsy was performed, 2020–2021
Proportions of stillbirths and neonatal deaths among near-term normally-formed singleton babies in 2020-2021 for which an autopsy was performed. In the majority of cases autopsies were not performed.
![](https://viz.aihw.gov.au:443/t/Public/views/PER101_sandia_tsnf_year_investigations_30072024/dash_chart.png?:embed=y&:showVizHome=no&:display_spinner=no&:host_url=https%3a%2f%2fviz.aihw.gov.au)
Draper ES, Kurinczuk JJ & Kenyon S (eds) on behalf of MBRRACE-UK 2015. MBRRACE-UK Perinatal Confidential Enquiry: Term, singleton, normally-formed, antepartum stillbirth. Leicester: The Infant Mortality and Morbidity Studies, Department of Health Sciences, University of Leicester.
Draper ES, Kurinczuk JJ & Kenyon S (eds) on behalf of MBRRACE-UK 2017. MBRRACE-UK Perinatal Confidential Enquiry: Term, singleton, intrapartum stillbirth and intrapartum-related neonatal death.
Flenady V, Wojcieszek AM, Middleton P, Ellwood D, Erwich JJ, Coory M, Khong TY, Silver RM, Smith GC, Boyle FM and Lawn JE (2016) ‘Stillbirths: recall to action in high-income countries’, The Lancet, 387:691–702, doi:10.1016/S0140-6736(15)01020-X.
RCOG (Royal College of Obstetricians and Gynaecologists) (2017) Each baby counts: 2015 summary report. London: RCOG, accessed 25 February 2021.
RCOG (2010) Late Intrauterine Fetal Death and Stillbirth: Green top guideline No.55, RCOG, accessed 15 September 2022.