Daily changes in sleep stages and associated cardiovascular parameters during pregnancy: using a wearable device

This longitudinal, observational study investigated how sleep architecture changes during pregnancy and how these nightly sleep stages relate to cardiovascular health markers. While most pregnancy sleep research has historically relied on subjective self-reporting through questionnaires, this study utilized the Oura ring wearable device to collect objective, continuous 5-minute interval data on sleep stages, resting heart rate (HR), and heart rate variability (HRV) in a group of 14 pregnant women (primarily Hispanic).

The research team monitored participants using the Oura ring throughout their pregnancies to track the onset, frequency, and duration of deep, REM, light, and awake sleep stages. By employing linear mixed models, they assessed daily shifts in these sleep characteristics while adjusting for maternal age and pre-pregnancy BMI. They further analyzed the relationship between these sleep variables and cardiovascular health metrics to understand the autonomic modulation occurring during nightly rest.

The study identified significant changes in sleep structure as pregnancy progressed. Specifically, researchers observed that the onset of deep sleep was delayed, and the frequency of deep sleep episodes decreased over time. The results demonstrated a distinct link between sleep stages and cardiovascular health: increased deep sleep was associated with more favorable cardiovascular markers (lower HR and higher HRV), which suggests greater parasympathetic nervous system activity. In contrast, higher REM sleep activity was associated with increased HR and decreased HRV. These findings indicate that wearable technology can effectively capture these critical physiological shifts in a home setting.

Sleep is increasingly recognized as a vital component of cardiovascular health, particularly during pregnancy, where sleep disturbances are linked to risks like gestational hypertension and preeclampsia. By documenting the objective decline in deep sleep and its correlation with cardiovascular strain, this study provides a foundation for developing personalized, non-invasive digital health interventions. Such technologies could help identify early warning signs of poor cardiovascular health and promote restorative sleep to improve maternal wellness.