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Answering the questions surrounding unexplained stillbirth

Mater researchers are gradually uncovering the mystery surrounding unexplained fetal death in Australia.

A four year study undertaken by the Stillbirth Prevention Research Team at Mater Mothers’ Research Centre, in collaboration with the Australian and New Zealand Stillbirth Alliance, revealed a number of risk factors for unexplained stillbirth.

The identified risk factors were: first pregnancies; mothers aged 35 years and over; women who were smokers at the antenatal booking visit, and women who gave birth to babies with a growth restriction.

From a population of Australian singleton births across three states, the study compared the characteristics of 808 unexplained stillbirths to a group of 693 normally formed stillbirths where a cause of death was identified, and a group of 837 liveborn healthy infants.

The study found that almost one-third of stillbirths were unexplained.

It identified that women with an unexplained stillbirth were less likely to have medical or pregnancy complications than women with explained stillbirths, but that complications occured more frequently in the unexplained stillbirth group when compared to those women having a healthy liveborn infant.

The study further identified that the majority of stillbirths were not adequately investigated and that therefore important information to explain the death may have been missed.

In Australia and New Zealand, the unexplained stillbirth rate is approximately two per 1000 births, and contributes to 30 per cent of all fetal deaths. The risk of unexplained fetal death increases with advancing pregnancy.

The study’s principle investigator Associate Professor Vicki Flenady said the results were an important breakthrough in the challenge to identify risk factors that are truly predictive of unexplained fetal death.

“Despite the frequency of unexplained stillbirths, little research has been undertaken in this area. From the available research, there is some evidence to suggest that factors which are potentially identifiable in the antenatal period may predict women at risk,” Associate Professor Flenady explained.

However, the studies were limited by methodological problems, resulting in inconclusive findings.

Associate Professor Flenady said there was an urgent need to clarify, from the list of reported risk factors, which of those are truly predictive of unexplained fetal death.

“The main aim of this study was to identify factors which predict women at increased risk of unexplained stillbirth in order to mount effective prevention strategies and future research aimed at reducing the number of these deaths,” she said.

On the basis of the study, women at increased risk can now be more confidently identified and appropriate antenatal care more effectively planned to reduce this risk.

Other implications for clinical practice resulting from the study included improvement of investigations and data collection for stillbirths. The study also established, for an Australian population, the significant contribution of fetal growth restriction to stillbirth, highlighting an important area for future research and practice improvement.

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