Normal pregnancy is characterized by progressive changes in sleep and physical activity as the pregnancy advances, he said. “But some patients don’t follow that clock.” When patients’ sleep and activity levels don’t change on a typical trajectory, the study showed, it’s a warning sign for premature birth, he added.

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As the pregnancies progressed, sleep typically became more disrupted, and women became less physically active, the study showed. However, some women’s sleep and activity patterns changed on an accelerated timeline relative to how far along they were in their pregnancies. These individuals were more likely to deliver early, the study found.

Risk Factors of Premature Delivery

Premature birth, when a baby is born 3 or more weeks early, affects 10.5% of births in the United States; these rates are higher in some other parts of the world. Premature newborns can suffer many medical complications, including diseases of the eyes, lungs, brain, and digestive system. Prematurity is the leading cause of death for children under age 5 around the world.

Research has identified a variety of risk factors for premature delivery, including greater levels of inflammation in the pregnant person, specific immune-system changes, African American race, higher levels of stress, history of having a preterm birth, and certain types of bacteria in the mother’s microbiome.

But doctors still can’t reliably determine which pregnancies are at risk for premature delivery. Even when they know a mom is at risk — because she’s previously had a premature delivery, for example — they still don’t have great treatments to extend the pregnancy closer to the due date. Developing medications that could do this would be complex, in part because of ethical concerns regarding testing drugs that might harm the fetus.

Evaluating Sleep and Activity Patterns in Pregnant Women with Machine Learning Model

The Stanford Medicine team collaborated with scientists at Washington University in St. Louis, who collected the sleep and physical activity data from 1,083 pregnant women treated there. More than half of the cohort (706 participants) were Black. In the United States, the rate of premature birth is about 50% higher in Black women than in white women.

“Our patient population experiences a lot of adversity, and our preterm birth rates are much higher than at Stanford,” said study coauthor Sarah England, PhD, professor of obstetrics and gynecology at Washington University School of Medicine in St. Louis. The study participants included women experiencing a variety of stressors linked with higher rates of preterm birth, such as racism, low socioeconomic status and living in areas with higher crime rates, England said, adding that it is important for studies of preterm birth to include populations with the greatest need.

The participants wore actigraphy devices similar to smartwatches to collect once-a-minute measurements of physical activity and light exposure starting in the first trimester of pregnancy and continuing until their babies were born.

The researchers also had data from participants’ electronic medical records on gestational age, or how far along each pregnancy was; maternal medical conditions such as high blood pressure, diabetes, heart disease and depression; pregnancy complications such as preeclampsia and infections; and information about the birth, including duration of the pregnancy, the baby’s birth weight and newborn medical complications.

With the movement and light exposure data, the research team developed a machine-learning model of activity and sleep during pregnancy. The model shows that patterns of sleep and physical activity change over the course of pregnancy, which generally is associated with more sleep disruption and less physical activity as pregnancy progresses.

The researchers were surprised at how strongly deviations from the normal pattern of sleep and physical activity could predict preterm birth. If the machine-learning model classified a woman as sleeping better and being more physically active than usual for her stage of pregnancy, this was linked with a 48% reduction in risk for preterm delivery.

Conversely, if the model classified a woman as sleeping worse and being less physically active than usual for her stage of pregnancy, her risk for preterm delivery was 44% higher than for pregnant women with typical sleep and activity patterns.

Sticking to Normal Circadian Rhythm Prevents Premature Birth in Pregnancy

The results suggest that scientists should run studies to test whether tracking and modifying pregnant women’s sleep or physical activity could lower prematurity risk, he said, adding, “It’s telling us where to go for future interventions.”

The circadian clock regulates several other biological pathways implicated in premature birth, such as those regulating inflammation and the immune response, the scientists said. They plan to test whether improving sleep and physical activity in pregnancy could modify other key pathways, such as those controlling inflammation.

Although the findings are at an early stage, and more work is needed to understand their implications for preventing pre-maturity, there’s little risk in advising pregnant women to maintain good sleep habits now, she added. For instance, women should try to maintain consistent bedtimes and wake-up times, get enough sleep, and get some natural light during the day to help regulate their body clock.

Reference :

1. Deep representation learning identifies associations between physical activity and sleep patterns during pregnancy and prematurity – (https://www.nature.com/articles/s41746-023-00911-x)

Source: Eurekalert