(655) Objective quantification of sleep throughout pregnancy, preterm birth, and delivery gestational age

Sleep quality and quantity (evaluated using traditional duration/stage measures and novel metrics including the sleep regularity index, a parameter assessing sleep pattern regularity and consistency) are associated with health outcomes. We sought to determine which sleep parameters are associated with PTB.


Study Design: Primary analysis of a prospective cohort enriched for those at high a priori risk of PTB. Participants identifying as Black, White, and/or Hispanic, with singleton, non-anomalous gestations were recruited < 14 weeks, 2017-2022. Participants were provided FitBit wristband activity trackers at enrollment and instructed to maintain their usual activity. Those with ≥7 nights of sleep monitoring (verified by FitBit recorded heart rate) were included. The primary outcomes were delivery gestational age and PTB < 35 weeks.  We evaluated individual sleep parameters and a composite ‘poor sleep’ score based on previously established metrics of sleep health. The poor sleep score was calculated by adding +1 point for (1) mean total min/asleep < 360 min/night; (2) mean % time in REM < 20%; (3) mean sleep efficiency (time asleep/time in bed) < 85%; (4) >50% of sleep midpoints ≥ 05:00; (5) ≥ 2 median night awakenings; (6) sleep regularity index in lowest quartile (< 95.2). Cox regression models included adjustments for multiple and differing numbers of observations per subject.

Results:

154 individuals were included, delivering at a median 38.2 (IQR 37.0, 39.3) weeks; 25% had PTB < 37 and 14% PTB < 35 weeks. The median sleep score was 2 (IQR 1,3); range 0-5. Clinical characteristics are shown in Table 1. Each sleep parameter’s variation over gestation is shown in Figure 1. In cox regression models, a poor sleep score (≥3; aHR 1.49, 95% CI 1.04, 2.13) and % time in REM sleep (aHR 0.21, 95% CI 0.06-0.73) were associated with delivery gestational age.


Conclusion:

Several sleep metrics vary across gestation, though tend to be similar among those with PTB < 35 weeks vs. those with later delivery. However, individuals with ≥3 poor sleep habits throughout pregnancy carried a higher risk of early delivery.