Research

Literature Review

ANZSA Literature Review on Stillbirth

ANZSA would like to acknowledge the Stillbirth Foundation Australia and the Department of Health and Aging for providing the funding for this review.

1. Purpose

The purpose of the review is to inform the development of an evidenced based approach to reducing the risk of stillbirth and to improving care for families in Australia and New Zealand (ANZ) experiencing a stillbirth through the development of recommendations for clinical practice and defining priorities for research.

2. Objectives

The objectives of this review are to:

A. To undertake a systematic literature review in order to summarise the best available research relevant to the Australia and New Zealand context on the following key areas:

a) causes and risk factors for fetal death;

b) antenatal prediction of stillbirth;

c) interventions to reduce the risk of stillbirth;

d) value and costs of stillbirth investigation protocols and their individual components;

e) bereavement support and options following a stillbirth

f) classification systems for stillbirth;

g) models for stillbirth audit.

B. To identify implications for practice and research from the above.


3. Methods

3.1 Intent of the review

The intention of this review is to summarise the currently available literature addressing the specific objectives. It is not the intent of this review to undertake analyses, including meta-analysis, or to undertake primary research to address gaps in the evidence but to highlight these areas as a part of recommendations for future research. Wherever possible, summaries of the evidence and recommendations from high quality systematic reviews or quality overviews and/or guidelines will be utilised.

3.2 Inclusion criteria

Publications
All identified published and unpublished reports (peer reviewed journal articles, guidelines, statements for professional colleges/organisations, regional and/or national statistics reports) on stillbirths which address the objectives of the review will be considered for inclusion. The search will focus on publications within the last 10 years, going further back in time only where more recent data are not available.

Population
All reports addressing one or more objectives of the review for stillbirths of 20 weeks gestation or 400 grams will be considered for inclusion.

Exclusions
Non-English language publications will be excluded. Studies and guidelines considered of poor quality according to the NHMRC and AGREE criteria respectively.
Systematic reviews and guidelines which were finalised >2 years at the time of the search will be supplemented by a literature search to ensure the most recent studies are identified.

3.3 Search strategy

A comprehensive search strategy will be developed based on clearly defined questions addressing each of the final review objectives.

The search will include an electronic database search and guideline web site search (Please see Appendix 1. for Guideline websites)

The following electronic databases will be searched: The Cochrane Library; MEDLINE (1970-2007); and CINAHL (1970-2007). Generic terms will be used, with additional terms for specific questions. Generic search terms will include: text terms; f?etal death, f?etal wastage, perinatal mortality, perinatal death, stillb*, and MeSH terms; fetal death and perinatal death. The generic search terms will be combined with question specific terms.

3.4 Search questions relating to the objectives

The following list of questions are provided as a starting point and may be modified following input form the review working party.

a) Causes and risk factors for fetal death

  • What are the main causes of fetal death in Australia?
     
  • What are the maternal, pregnancy and fetal factors which are independently associated with an increased risk of stillbirth?
    o Including the effects of: previous obstetric history (Caesarean section, Fetal Growth Restriction, low birthweight, stillbirth, perinatal death, preterm birth); gestational age; smoking status, maternal age, maternal overweight and obesity, fetal growth restriction, placenta and cord abnormalities (cord torsion and knots); reporting of reduced fetal movements preceding fetal death; Plurality; ART; chorionicity; ethnic background, specifically: Australian Aboriginal; Torres Strait Islander, Pacific Islander and Maori; maternal lifestyle factors: smoking, diet, alcohol, other substance use, exercise, employment.
     
  • What is the gestational age specific risk of fetal death by cause according to plurality (singleton, twins and higher order multiples) and timing of death (antepartum versus intrapartum)? And how do the known risk factors modify this risk?
     
  • What are the factors associated with unexplained stillbirth according to gestation?
     
  • What is the recurrence risk of stillbirth? How does this risk differ according to causes and risk factors of fetal death?

b) Antenatal prediction of stillbirth

  • What is the performance of current screening tests for fetal death according to low and high risk pregnancies?
     
  • Including: ultrasound scan; markers of early placental dysfunction (PAPP-A); fetal movement monitoring; risk scoring systems in the antenatal period

c) Interventions to reduce the risk of stillbirth

What are the effects of pre-pregnancy and antenatal interventions, including costs, to reduce the risk of fetal death?

The search will include the following:

  • components of routine antenatal care and testing including: number of antenatal visits; surveillance measures for low and high risk pregnancies eg urine testing, blood pressure monitoring; weighing; ultrasound scans, CTG, VAS, specific fetal growth surveillance (serial ultrasound; customised fetal growth centiles; fundal height measuring and customised fundal height.)
     
  • fetal movement monitoring: KICK charts; ambulatory monitoring.
     
  • management of women reporting reduced felt movements
     
  • strategies to promote smoking cessation in pregnancy
     
  • models of antenatal care;
     
  • management of fetal growth restriction in the antenatal period
     
  • screening and treatment for maternal thrombophilia
     
  • timing of delivery
     
  • pre-pregnancy counselling/public health campaigns on prevention including: diet, folic acid supplementation, maternal weight, smoking, advanced maternal age.

d) Value and costs of stillbirth investigations protocols and their individual components

The specific questions relating to investigation of the causes of stillbirth aim to identify:

  • the yield of useful information and costs of stillbirth investigation protocols and their individual components;
     
  • the affect of quality of autopsy on the yield of useful information;
     
  • the utility of a non-selective versus a selective protocol for investigation of stillbirth;

e) Bereavement support and options following a stillbirth

What are the experiences and choices of parents after a stillbirth (including autopsy and holding baby) associated with improved short and longer term psychosocial outcomes for parents and families?

f) Classification systems for stillbirth

How do the contemporary classification systems of stillbirths perform in terms of agreement and satisfaction by users?

g) Models for stillbirth audit

What are the current audit models for stillbirth including the identification of potentially preventable factors for stillbirth?
Including the following aspects of audit: Multidisciplinary versus trained coder; central versus hospital committee.

3.5 Selection of studies, quality assessment and data collection.

The search strategy will be developed by two of the project team members and will work collaboratively to identify a list of potentially eligible publications for closer assessment. Two reviewers will assess quality, compare results and resolving differences, and undertake data collection. Reasons for exclusions will be reported for all publications which were initially considered on the initial screen to be potentially eligible.

3.6 Grading the quality of the evidence

NHMRC Guidelines on grading the evidence will be applied to the identified studies. Studies considered to be of poor quality will be excluded.

3.6.1 Systematic reviews and individual study reports

Two grading systems will be used to determine the quality of the literature identified from the searches: 1) Level of evidence; and (where recommendations are made) the 2) Strength of recommendation

Levels of Evidence
As defined in "A Guide to the Development, Implementation and Evaluation of Clinical Practice Guidelines" (National Health & Medical Research Council, Canberra, 1999).
Level Criteria
Level I evidence obtained from a systematic review of all relevant randomised controlled trials
Level II evidence obtained from at least one properly designed randomised controlled trial.
Level III-1 evidence obtained from well-designed pseudo-randomised controlled trials (alternate allocation or some other method).
Level III-2 evidence obtained from comparative studies with concurrent controls and allocation not randomised (cohort studies), case control studies, or interrupted time series with a control group.
Level III-3 evidence obtained from comparative studies with historical control, two or more single-arm studies, or interrupted time series without a parallel control group
Level IV evidence obtained from case series, either post-test or pre-test and post-test.

3.6.2 Strength of recommendation grading

A grading for the overall strength of each recommendation will also be applied. The grading system, previously used by the project team, was modified from that used by the Royal College of Obstetricians and Gynaecologists in the United Kingdom ( www.rcog.org.uk) as follows:

Grade Criteria
A Requires at least one randomised controlled trial as part of a body of literature of overall good quality and consistency addressing the specific recommendation (Evidence Level I or II)

B Requires the availability of well-conducted clinical studies on the topics of the recommendation (Evidence levels III-1, III-2, III-3 or Level I or II evidence where the dimensions of the evidence internal validity, statistical precision, size of the effect and relevance are considered to limit the strength of the evidence )

C Requires evidence obtained form expert committee reports or opinions and/or clinical experience of respected authorities. Indicates an absence of directly applicable clinical studies of good quality (ie where the dimensions of the evidence internal validity, statistical precision, size of the effect and relevance are considered to limit the strength of the evidence)

Good practice points
 Recommended good practice based on the clinical experience of the expert panel.

3.6.3 Guidelines

Existing guidelines will be assessed for quality and relevance using the AGREE instrument by two independent reviewers. (The AGREE Collaboration. Appraisal of Guidelines for Research and Evaluation (AGREE) instrument. www.agreecollaboration.org.) A decision to include all or components of the guidelines in this review will be made by consensus.

3.6.4 Epidemiological data on stillbirth risk

The working party will define the quality assessment tool prior to commencing the search. Non-population based data will only be included where population based data are lacking.

3.7 Data presentation

Risk
Stillbirth rates will be presented as the number of stillbirths/ the total number of births X 1000.
Gestational age specific fetal death risk will be defined using the number of ongoing pregnancies in each gestational age window as the denominator (i.e. the number undelivered at the start of each week minus the number of stillbirth and livebirths occurring in that week).

Outcomes of interventions
Relative risks 95% confidence intervals, with number needed to treat and number needed to harm will be reported where appropriate.