An investigation of fetal behavioural states during maternal sleep in healthy late gestation pregnancy: an observational study

Abstract

Fetal behavioural states (FBS) are measures of fetal wellbeing. Maternal position affects FBS with supine position being associated with an increased likelihood of fetal quiescence consistent with the human fetus adapting to a lower oxygen consuming state. Several studies have now confirmed the association between sleep position and risk of late intrauterine death. We designed this study to observe the effects of maternal sleep positions overnight in healthy late gestation pregnancy. Twenty-nine healthy women had continuous fetal ECG recordings overnight. Two blinded observers assigned fetal states in 5 min blocks. Measures of fetal heart rate variability (FHRV) were calculated from ECG beat to beat data. Maternal position was determined from infrared video recording. Compared to state 2F (active sleep), 4F (active awake-high activity) occurred almost exclusively when the mother was in a left or right lateral position. State 1F (quiet sleep) was more common when the mother was supine [odds ratio (OR) 1.30, 95% confidence interval (CI) 1.11-1.52] and less common on the maternal right side with the left being the referent position (OR 0.81, 95% CI, 0.70-0.93). State 4F was more common between 21.00 and 01.00 h than between 01.00 and 07.00 h (OR 2.83, 95% CI 2.32-3.47). In each fetal state, maternal position had significant effects on fetal heart rate and measures of FHRV. In healthy late gestation pregnancy, maternal sleep position affects FBS and heart rate variability. These effects are probably fetal adaptations to positions which may produce a mild hypoxic stress.

Assessment of autonomic function in the late term fetus: The effects of sex and state

“…With regard to withinsubjects analyses, marginal differences were found in RMSSD by state, with lower values for 1F than 2F. However, these findings follow a similar pattern of other research that used overnight recordings and found RMSSD to be lower in 1F when compared to 2F (Stone et al, 2017). Our results suggest that differences in RMSSD as a function of state should be examined as an individual characteristic.…”

Effects of maternal sleep position on fetal and maternal heart rate patterns using overnight home fetal ECG recordings

“…24 No effect of maternal position on FHR was reported in a study by Ibrahim et al 21 as well as in the home. 25 These investigators reported that, compared with the left side, FHR during supine position was slightly increased, and that both right and supine were associated with reduced SDNN, whereas only supine was associated with decreased RMSSD. 22,25 The present study did have some limitations, including the identification of position using the Embletta system rather than with video monitoring.…”

“…25 These investigators reported that, compared with the left side, FHR during supine position was slightly increased, and that both right and supine were associated with reduced SDNN, whereas only supine was associated with decreased RMSSD. 22,25 The present study did have some limitations, including the identification of position using the Embletta system rather than with video monitoring. This choice was made in the interest of minimizing invasiveness with respect to privacy concerns and participant comfort.…”

Waking up too early – the consequences of preterm birth on sleep development

“…A recent study showed that maternal sleeping position can also alter the behavioural sleep states of late gestation fetuses, as determined by fetal heart rate variability (Stone et al . ). This study demonstrated that, compared to 2F, 4F activity was seen almost exclusively when the mother was in a left or right lateral position, while 1F was more common when the mother was supine (Stone et al .…”

“…This study demonstrated that, compared to 2F, 4F activity was seen almost exclusively when the mother was in a left or right lateral position, while 1F was more common when the mother was supine (Stone et al . ). Further, 4F was more common between 21.00 and 01.00 h than between 01.00 and 07.00 h (Stone et al .…”