Accuracy of self-reported sleep position in late pregnancy

PLoS One. 2014 Dec 23;9(12):e115760. doi: 10.1371/journal.pone.0115760. eCollection 2014.


Background: There is emerging research to suggest that supine maternal sleep position in late pregnancy may adversely affect fetal wellbeing. However, these studies have all been based on maternal report of sleeping position. Before recommendations to change sleep position can be made it is important to determine the validity of these studies by investigating how accurate pregnant women are in reporting their sleep position. If avoiding the supine sleeping position reduces risk of poor pregnancy outcome, it is also important to know how well women can comply with the instruction to avoid this position and sleep on their left.

Method: Thirty women in late pregnancy participated in a three-night observational study and were asked to report their sleeping position. This was compared to sleep position as recorded by a night capable video recording. The participants were instructed to settle to sleep on their left side and if they woke overnight to settle back to sleep on their left.

Results: There was a moderate correlation between reported and video-determined left-side sleep time (r = 0.48), mean difference = 3 min (SD = 3.5 h). Participants spent an average of 59.60% (SD = 16.73%) of time in bed on their left side (ICC across multiple nights = 0.67). Those who included left side among their typical sleep positions reported significantly longer sleep during the study (p<0.01).

Conclusions: On average participant reports of sleep position were relatively accurate but there were large individual differences in reporting accuracy and in objectively-determined time on left side. Night-to-night consistency was substantial. For those who do not ordinarily sleep on that side, asking participants to sleep on their left may result in reduced sleep duration. This is an important consideration during a sleep-critical time such as late pregnancy.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Female
  • Humans
  • Pregnancy
  • Pregnancy Complications / etiology*
  • Self Report
  • Sleep*
  • Supine Position*
  • Young Adult

Grant support

The project was funded by a University of South Australia School of Nursing and Midwifery research development grant. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.