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This article is part of the supplement: Proceedings of the Stillbirth Summit 2011

Open Access Oral presentation

Sleep practices and risk of stillbirth: implications for prevention and research

Edwin A Mitchell

Author affiliations

University of Auckland, New Zealand

Citation and License

BMC Pregnancy and Childbirth 2012, 12(Suppl 1):A13  doi:10.1186/1471-2393-12-S1-A13


The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2393/12/S1/A13


Published:28 August 2012

© 2012 Mitchell; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Oral presentation

Stillbirth research is hindered by a lack of a uniform definition and a lack of an internationally agreed protocol for the investigation of a death. However, the major issue is that not all stillbirths have an autopsy [1], and many are not investigated at all.

Mortality reviews (case series) are descriptive and hypothesis generating. In New Zealand the Perinatal and Maternal Mortality Review Committee reviews all deaths from 20 weeks gestation to 28 completed days after birth, or weighing at least 400g if gestation is unknown [2]. In 2009 the stillbirth rate was 6.3/1000 births. 25% were unexplained, and half of these occurred at term. 22% were not investigated. Maori and Pacific mothers were at higher risk and rates were increased in the most deprived socioeconomic quintile. Teenage mothers and those 40+ years were also at higher risk. Maternal obesity, multiple pregnancy and maternal medical conditions were also associated with risk of stillbirth. Only 15% of stillbirths were potentially avoidable. Although much can be learnt from examining national mortality databases, these do not allow examination of risk factors which are operating close to the demise of the fetus.

Case control studies are an efficient way to examine such risk factors. A small number of studies have been completed [3,4] or are still collecting data. The Auckland Stillbirth Study, a three year case-control study, had a particular focus on modifiable risk factors, including that related to maternal sleep [3]. We found an increased risk of stillbirth with non-left sleep position, regular sleep during day-time, more than 8 hours of night-time sleep and getting up to the toilet once or less per night [5]. The prevalence of non left sided sleep position in this study was 57.3% and the population attributable risk for non-left sided sleep position was 37%. Therefore, if there is a causative pathway between maternal sleep position and late stillbirth, over a third of late stillbirths (in high income countries) could be attributable to maternal sleep position. Further studies need to be conducted as soon as possible to determine whether this finding is reproducible and if confirmed, it would then be appropriate to instigate public health campaigns to encourage women to go to sleep on their left side in late pregnancy.

Research is needed to show how best to implement the findings. One testable hypothesis is that sleeping on the left side of the bed encourages mothers to sleep on their left side. A survey in Auckland is currently underway to examine this.

Furthermore, physiological studies of the pregnant mother and the fetus are required, such as examining the effect of maternal body position on cardiac output, uterine blood flow and on fetal wellbeing. There needs to be sleep studies of normal pregnant mothers in late pregnancy as well as longitudinal studies over the last trimester and possibly beginning at 20 weeks gestation.

References

  1. Gordon A, Jeffery HE: Classification and description of stillbirths in New South Wales, 2002-2004.

    Med J Aust 2008, 188(11):645-8. PubMed Abstract | Publisher Full Text OpenURL

  2. PMMRC: Fifth annual report of the Perinatal and Maternal Mortality Review Committee: Reporting mortality 2009. [http://www.pmmrc.health.govt.nz] webcite

    Wellington: Health Quality & Safety Commission; 2011.

  3. Stacey T, Mitchell EA, Thompson JMD, Ekeroma AJ, Zuccollo JM, McCowan LME: The Auckland Stillbirth study, a case control study exploring modifiable risk factors for third trimester stillbirth: methods and rationale.

    Aust N Z J Obstet Gynaecol 2011, 51(1):3-8.

    doi: 10.1111/j.1479-828X.2010.01254.x. Epub 2010 Dec 6

    PubMed Abstract | Publisher Full Text OpenURL

  4. Stillbirth Collaborative Research Network Writing Group: Association between stillbirth and risk factors known at pregnancy confirmation.

    JAMA 2011, 306(22):2469-79. PubMed Abstract | Publisher Full Text OpenURL

  5. Stacey T, Thompson JM, Mitchell EA, Ekeroma AJ, Zuccollo JM, McCowan LM: Association between maternal sleep practices and risk of late stillbirth: a case-control study.

    BMJ 2011, 342:d3403. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL