If you’ve ever tossed and turned through the early weeks of pregnancy, unsure whether your changing sleep patterns meant anything more than discomfort or hormones—you’re not alone. And now, a groundbreaking new study says those restless nights might be telling doctors something important.
Preterm birth is the leading cause of infant death around the world. Yet for decades, healthcare providers have struggled to predict which pregnancies are at risk until it’s too late. That may finally be changing.
Researchers at Washington University in St. Louis have uncovered a surprising signal: inconsistent sleep patterns in early pregnancy may help predict preterm birth. With the help of wearable devices and machine learning, doctors may soon have a noninvasive, tech-powered tool to identify risk long before symptoms appear.
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What the study found
A new study in npj Women’s Health explored whether sleep patterns in early pregnancy could help predict preterm birth and the results are promising.
Researchers at Washington University in St. Louis analyzed sleep data from 665 pregnant participants who wore actigraphs (wrist-worn devices that track movement) during their first two trimesters. This allowed the team to capture objective, continuous data—like bedtime consistency and total sleep time—rather than relying solely on self-reported surveys.
The key finding? It wasn’t the number of hours of sleep that mattered most—it was the consistency of sleep patterns. Using machine learning models, the researchers found that greater variability in sleep—like shifting bedtimes or irregular sleep lengths—was more strongly linked to preterm birth than overall sleep quality or duration.
This is one of the first large-scale studies to use wearable sleep data in this way, suggesting that subtle changes in sleep rhythm could reflect early signs of physiological stress during pregnancy.
Related: Getting COVID-19 during pregnancy can mean a higher risk of preterm birth—and maternal death
Why this changes the game
For years, predicting preterm birth has felt like educated guesswork, often relying on a mix of family history, symptoms that appear too late, or vague risk factors. This new research introduces a different possibility: a measurable early signal from the body that providers can act on.
What makes this study stand out is the timing. The researchers focused on sleep patterns collected before 20 weeks of pregnancy, well before the third trimester when sleep disruptions are more common. That opens the door to earlier identification and intervention, months ahead of current methods.
Equally important: the technology wasn’t overly complex or inaccessible. The machine learning models used were intentionally simple and interpretable, making the findings more likely to be adopted in clinical practice. And because actigraphy devices are wearable and noninvasive, this kind of monitoring could realistically happen at home.
This research points to a shift in care—one that supports earlier detection and more proactive care plans.
What it means for moms
For many expecting moms, especially in early pregnancy, sleep can feel like a moving target. Nausea, anxiety, physical discomfort, and hormonal shifts can all wreak havoc on rest. And for years, the medical system has often brushed this off as “normal” or unimportant.
This research adds weight to what many pregnant people already suspected—restless nights might hold clues about more than just fatigue. And the earlier those clues are noticed, the better support providers can offer.
What’s especially reassuring is that the predictive signal came from sleep variability. The researchers found that fluctuating bedtimes and inconsistent schedules told them more than the number of hours slept. A steady rhythm—even with occasional rough nights—was more meaningful in predicting outcomes than aiming for flawless sleep.
The goal is to use sleep data as a window into your body’s experience—to inform care, not add pressure.
What to know about sleep and pregnancy
Sleep in pregnancy is complex—and not just because of growing bellies and middle-of-the-night bathroom runs. Hormonal changes, increased metabolism, and even changes in breathing patterns can all impact how well you rest.
Here are a few quick facts to keep in mind:
- Sleep needs increase during pregnancy, especially in the first trimester, due to rising progesterone levels.
- Disrupted sleep is common, even early on. But persistent changes—like staying up much later than usual or waking multiple times—can be worth tracking.
- Poor sleep has been linked in previous research to gestational diabetes, high blood pressure, and mood disorders during pregnancy. Now, preterm birth is being added to that list.
Sleep changes don’t mean you’re doing anything wrong. But they can offer valuable insight into how your body is handling the demands of pregnancy and give your care team another way to support you.
Why sleep patterns—not just sleep length—might matter
We often focus on how much sleep we get, but new research suggests that how consistent your sleep is might be just as important—especially during pregnancy.
In the study, researchers found that:
- People with more variable sleep patterns (frequent changes in bedtime, wake time, and sleep duration) had a higher likelihood of preterm birth.
- Even if total sleep hours were similar, irregular sleep schedules were more predictive of early delivery than consistently short sleep.
Why might this matter? Your body’s internal clock, or circadian rhythm, plays a key role in regulating hormones, immune responses, and inflammation—all of which are critical during pregnancy. Disrupting that rhythm repeatedly could signal stress your body is under, even if you’re not consciously aware of it.
The takeaway: Your body does best when it can rely on a steady sleep rhythm—not flawless sleep, just consistent cues.
Tips for setting a consistent sleep schedule in early pregnancy
Sticking to a regular sleep routine during pregnancy can feel impossible—but small changes can go a long way. Here are a few gentle, realistic strategies to help your body settle into a rhythm:
- Anchor your wake-up time. Even if your bedtime shifts, waking up at the same time each morning helps reset your internal clock.
- Wind down the same way each night. A short, calming routine (like dimming lights, light stretching, or reading) signals to your brain that sleep is coming.
- Limit screens close to bedtime. Blue light can disrupt melatonin production—try switching to night mode or putting devices away 30–60 minutes before bed.
- Watch for naps that shift your schedule. Rest is important, but long or late naps can make it harder to fall asleep at night.
- Be kind to yourself. Some nights will still be rough, and that’s okay. Consistency doesn’t mean perfection—it just means trying to find a pattern your body can rely on.
The goal is to create a rhythm your body can rely on during a time of big change—even if some nights are still unpredictable.