In a study of 41 first-time mothers, researchers tracked sleep from before pregnancy through 13 weeks postpartum using wearable devices. Participants, aged 26 to 43, wore Fitbits continuously from a 1 year before delivery through the first year after birth.
During the first postpartum week, average daily sleep time dropped to 4.4 hours, compared to 7.8 hours prior to conception. The longest uninterrupted sleep stretch also declined to 2.2 hours, down from 5.6 hours preconception. Nearly one-third of participants (31.7%) went more than 24 hours without any measurable sleep.
Sleep duration improved in subsequent weeks. Between weeks 2 and 7 postpartum, mothers averaged 6.7 hours of sleep per day, compared to 7.7 hours before pregnancy. By weeks 8 to 13, sleep increased to 7.3 hours, nearing the preconception average of 7.9 hours.
However, sleep consolidation remained reduced throughout the 13-week period. In weeks 2 to 7, the average longest uninterrupted stretch of sleep was 3.2 hours, compared to 5.5 hours preconception. In weeks 8 to 13, it rose slightly to 4.1 hours, still below the pre-pregnancy level of 5.6 hours.
All differences in sleep duration and continuity were statistically significant (F > 29.8; P < .001).
To measure sleep, researchers analyzed wearable data in 5-minute segments and defined sleep onset and offset using at least 10 minutes of continuous sleep or wake activity. Days without heart rate data—suggesting the device was off—were excluded.
The study used “longest stretch of sleep” (LSS), a metric commonly applied to infant sleep, to assess sleep consolidation in adults. While overall sleep duration returned to near baseline, the ability to sleep in longer uninterrupted blocks did not.
These findings suggest that fragmented sleep patterns persist through the first 3 months after childbirth and may warrant further investigation for their impact on maternal health.
The research abstract was published recently in an online supplement of the journal SLEEP and will be presented during SLEEP 2025 in Seattle. The study was supported by a private sleep analytics company.
Source: Sleep
