Pregnant women who experienced late stillbirth appear less likely to have slept on their left
- School of Nursing and Midwifery, University of South Australia, Division of Health Sciences, Adelaide, South Australia, Australia
- Correspondence to Jane Warland
School of Nursing and Midwifery, Division of Health Sciences, University of South Australia, North Tce, Adelaide, SA 5000, Australia;
Implications for nursing practice
■ There is some evidence that settling to sleep in the left position may reduce the risk of stillbirth.
■ For women in late pregnancy getting up more than once overnight may also reduce the risk of stillbirth.
Implications for nursing research
■ There is a need for further research to ascertain the extent to which sleeping on the left side is protective for stillbirth.
■ This research should also explore the point in the pregnancy at which it is important to adopt a left-lying sleeping position.
Research into modifiable and preventive risk factors for stillbirth is emerging as an area of research interest across the globe.1 Adding to this body of research is a new study conducted in New Zealand.
A total of 465 women were enrolled in this case-control study. The cohort consisted of 155 cases (stillborn) and 310 matched live born controls. This study set out to broadly explore modifiable risk factors for late stillbirth.
Stacey and colleagues have previously reported findings from this study.2 In this report, specific findings concerning maternal sleep practices and risk of late stillbirth are given. They indicate that women in late pregnancy who reported settling to sleep on their back or on their right side were at increased risk of stillbirth (OR 1.8, 95% CI 1.1 to 2.8).
This finding is interesting from two points of view: it makes sense physiologically and practically. It is well documented that left lateral position is the ideal position for pregnant women when resting or sleeping, in terms of maternal cardiac output and fetal oxygen saturation.3 4 Indeed, pregnant women tend to naturally adopt this position for sleep.5 It is also common practice in many parts of the world to advise women to settle to sleep on their left.6 Furthermore, it is standard practice to shift a labouring woman onto her left side during acute fetal distress, as this position aids fetal recovery.7
Stacey and colleagues also reported that women who get up more than once overnight may be protected against stillbirth compared with women who rise only once or sleep through the night (adjusted OR 2.28). They do not postulate what the mechanism for this may be. This finding may be related to maternal hypotension. Another study8 found women who consistently had borderline low blood pressure during pregnancy were at increased risk of stillbirth (OR 1.78, 95% CI 1.06 to 2.88, p=0.03). This may be because there is a physiological drop in blood pressure during sleep. If the pregnant woman gets up during the night, her blood pressure will rise compared with a woman who continues to sleep through, and this may be what makes getting up protective.
The present study has some limitations. For example, the authors were not able to ascertain changes in sleep position during the night. It is well known that people shift position many times during sleep when they are not pregnant. A large pregnant abdomen and the fact that many pregnant women sleep supported by pillows may reduce the number of times women change position as they sleep. Stacey and colleagues did find that the participant report of the position they fell asleep in and the position they woke in was highly correlated (Pearson correlation coefficient r=0.72, p<0.001) perhaps suggesting that pregnant women do not change position to the same extent as the non-pregnant.
The authors suggest that further research is required before any public health recommendations can be made. This kind of caution is standard especially when reporting a novel finding. However, given the fact that these findings make physiological and practical sense, it would seem prudent for care providers to, at least, discuss left-sleeping position with pregnant women. In conclusion, although further research is needed, encouraging pregnant women to sleep on their left side may be an important step in reducing the risk of stillbirth.