Seeking Stillbirth Solutions - The Auckland Stillbirth Study

Tomasina Stacey

PhD Student

Obsetrics and Gynaecology/Paediatrics

University of Auckland

Background to research

The overall rate of stillbirths in New Zealand is increasing, after a decline in the 1980s and 1990s, and currently 400 babies are stillborn every year.

This is higher than the road toll and more then six times the rate of sudden unexpected death in infancy (SUDI). Approximately 200 of these babies die in utero at, or after 28 weeks gestation (third trimester stillbirth), which is a rate of 1 in 300 births. If these babies had been born live more than 90% of them would probably have survived.

In developed countries, the most common cause of third trimester stillbirth is classified as “unexplained” or “unspecified.” In addition to the overall rate of stillbirth increasing, it appears that the proportion of New Zealand stillbirths that are unexplained, is also increasing.

The risk factors that are known to be associated with unexplained stillbirth include advanced maternal age, high pre-pregnancy body mass index (BMI), smoking, fewer than four antenatal visits and low socio-economic status. A high proportion of unexplained (or unexpected stillbirths) is related to intrauterine growth restriction. The increasing trend (in the industrialised world) for women to have children later in life, and the increasing rate of obesity, may impact upon the number of stillbirths that are currently defined as unexplained.

What are your research objectives?

Ultimately our aim is to reduce the number of stillbirths that occur in New Zealand.

The specific objectives are to:

• To identify and quantify risk factors for third trimester stillbirth.
• To examine the prevalence of risk factors in the major ethnic groups (Maori, Pacific Island, European).
• To identify novel modifiable risk factors for third trimester stillbirth.

How will you conduct your research?

The study is a prospective case control study of third trimester stillbirths in the Auckland Region. Data collection was carried out over three years (from 1 July 2006-30 June 2009) in the 3 Auckland District Health Boards: Waitemata (WDHB), Auckland (ADHB) and Counties Manukau (CMDHB).

The study included all women who were booked to give birth in Auckland during the study period and had a third trimester stillbirth, other than women with multiple pregnancies, and those where the baby had a significant congenital abnormality.

Data were collected from clinical records and a face-to-face interview. The clinical data collection explored standard variables, associated with maternal medical and obstetric history, and the health of the woman and the baby through the current pregnancy. The interview covered areas such as:

● Socio-economic factors: maternal and paternal job status
● General health and access to alternative and complementary therapies.
● Maternal dietary intake.
● Sleep habits
● Exercise, work habits and daily activities
● Support
● Stress and depression
● Domestic violence

Controls were randomised from the booking lists of the respective District Health Boards. They were matched to the cases by gestation alone. Over the last three years more than 70% of women who experienced a third trimester stillbirth in Auckland participated in the study (155 cases and 310 controls; the target had been between 120 and 150 cases). Recruitment for the study is now complete and the research is now in the analysis stage.

Are there others in your field, in New Zealand or globally, conducting similar research?

There have been no prospective studies into risk factors for stillbirth conducted in New Zealand. A retrospective study that explored risk factors for late stillbirth in New Zealand, indicated that there is an increased risk for Pacific Island, Maori and Indian women, women living in low decile areas and for women of advanced maternal age. This retrospective study shed some light on the risk factors for third trimester stillbirth, but because of limited data was not able to investigate a wide number of variables.

The significance of stillbirth, and the need to gain a greater understanding of its causes, has recently been recognised. There are, therefore, a number of international studies that are being carried out into risk factors for unexplained stillbirth.

These include the Stillbirth Collaborative Research Network (SCRN USA), and in Australia, a population based epidemiological study (a National Health and Medical Research Council funded study in association with the Perinatal Society of Australia and NZ).

What is innovative about the approach you are taking?

The emphasis in other international studies is on medical and obstetric complications leading to stillbirth, and on standard epidemiological variables (such as maternal age and education). In contrast, the emphasis in The Auckland Stillbirth Study is on environmental and maternal lifestyle factors. Our study is unique in this regard. The nature of face-to-face interviews allows for greater depth in the questions asked of recently bereaved mothers.

If you are successful with your objectives what will that mean to those suffering from the disease or to the knowledge advancement of this disease?

Once there is a greater understanding of the causes of third trimester stillbirth, preventative strategies can be put into place to reduce the number of stillbirths that occur.

Is there is an international or national collaboration on your project?
We are sharing some research tools with the Stillbirth Collaborative Research Network.