Near-term singleton perinatal deaths without congenital anomaly

Perinatal deaths that occur 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 gestation.

For the purposes of this report, such babies are called ‘near-term normally-formed singleton babies’ and are of particular interest when considering potential avoidability in relation to perinatal deaths.

In 2015 and 2016, perinatal deaths of near-term normally-formed singleton babies:

  • accounted for 770 perinatal deaths (1.33 per 1,000 births), of which, 623 (80.9%) were stillbirths and 147 (19.1%) were neonatal deaths.
  • were higher among babies born to women aged under 20 (2.50 per 1,000 births).
  • decreased as the number of antenatal visits increased.
  • were more likely among babies born to women who reported smoking throughout pregnancy (2.42 per 1,000 births).
  • were more likely to occur in babies born to women who had pre-existing diabetes (4.25 per 1,000 births).
  • were more likely to occur in babies born to women with a BMI of 30.0 or more (obese) (1.51 per 1,000 births).
  • were higher for babies small for gestational age (less than the 10th percentile) (3.2 per 1,000 births).
  • were most likely at 36 weeks gestation (6.2 per 1,000 births).

Timing and cause of perinatal death

The most commonly classified causes of perinatal death for near-term normally-formed singleton babies were:

  • Unexplained antepartum death (36.6%)
  • Perinatal infection (13.5%).

These causes were similar for stillbirths (45.3% and 13.5%, respectively). For neonatal deaths, the most commonly classified causes were hypoxic peripartum death (31.3%) and no obstetric antecedent (25.9%).

The majority of perinatal deaths among near-term normally formed singleton babies occurred prior to the onset of labour (antepartum stillbirth) (73.8%).

Causes of perinatal deaths among near-term normally-formed singleton babies varied by birthweight percentile. The majority (69.5%) of babies who died had a birthweight appropriate for their gestational age.

Investigation following perinatal death

As unexplained antepartum death, hypoxic peripartum death and deaths with no obstetric antecedent rank highly as causes of perinatal death in near-term normally-formed singleton babies, investigations such as autopsy and placental histology examination are of particular importance in establishing the cause of death.

Autopsy

Of the 770 perinatal deaths among near-term normally-formed singleton babies, 737 had a stated autopsy status. Of deaths where autopsy status was stated in 2015 and 2016:

  • Autopsies were performed more frequently than for perinatal deaths occurring across all babies (57.7% and 41.1%, respectively).
  • Autopsies were performed more frequently in relation to neonatal deaths, with the highest proportion being performed in very early (less than 24 hours) neonatal deaths (75.0%).
  • The incidence of autopsy varied depending on the cause of death, with 52.6% of deaths due to hypoxic peripartum death undergoing an autopsy compared to 71.7% of deaths due to fetal growth restriction.

Placental examination

Data on placental histology examinations are not available for Queensland, Western Australia or South Australia. Data from these states have been excluded from analysis (refer to Data quality and availability of national perinatal mortality data for more information).

Of the 770 perinatal deaths among near-term normally-formed singleton babies in 2015 and 2016, there were 441 from News South Wales, Victoria, Tasmania, Australia Capital Territory where placental histology status was stated. Of deaths where placental histology status was stated:

  • There were 394 placental histological examinations performed.
  • Placental histological examinations were performed in 9 out of 10 stillbirths and 6 out of 10 neonatal deaths.