Nearly half of pregnant women in the United States report poor sleep quality, which has been associated with gestational diabetes and high blood pressure during pregnancy. A new study led by researchers at Washington University in St. Louis’ Bursky School of Public Health found that depression symptoms, prenatal distress and anxiety are the strongest predictors of poor sleep during late pregnancy, with environmental exposures such as air pollution and noise also playing significant roles.
While previous studies have examined individual contributors to poor sleep, the new research evaluated dozens of social, environmental and health factors to better understand how they work together. The findings were published online in June and will appear in the September print issue of Environmental Research.
Sleep problems often worsen during late pregnancy, when about 80% of women experience more sleep disturbances than at any other time in their lives. Common complaints include frequent awakenings, frequent urination, restless legs, fetal movement and sleep-disordered breathing. In late pregnancy, sleep disturbances can potentially affect birth outcomes and the long-term health of the mother and baby.
Senior author Carrie V. Breton, a professor at WashU Bursky Public Health, collaborated with first author Xiaoran Yang, a recent PhD graduate from the University of Southern California (USC) and WashU Professor Tracy M. Bastain, as well as other researchers from USC, the University of California, Irvine, and California State University, Northridge.
The researchers analyzed data from 687 pregnant women participating in the MADRES (Maternal and Developmental Risks from Environmental and Social Stressors) cohort, a long-running study of predominantly low-income Hispanic and Latina women in Los Angeles. Hispanic women remain underrepresented in U.S. sleep research despite experiencing higher rates of sleep problems than white populations.
Before joining WashU Bursky Public Health, Breton and Bastain helped build and co-lead the MADRES Center of Excellence on Environmental Health Disparities. Although the cohort remains based in Los Angeles, the research program continues as a collaboration between WashU and USC.
Overall, 26.3% of participants in the study reported poor sleep quality during late pregnancy.
Researchers used machine learning to evaluate 59 potential influences on sleep quality, including mental health, pregnancy health, physical activity, diet, neighborhood characteristics, air pollution, traffic-related pollution, noise, temperature and exposures to toxic metals and chemicals.
“We found that mental health was one of the strongest predictors of poor sleep during pregnancy, but environmental exposures, including air pollution and other pollutants, also played important roles,” Breton said. “Together, these findings reinforce that maternal health is shaped by multiple, interconnected social and environmental factors.”
The findings suggest that sleep quality during pregnancy is influenced not only by personal factors, such as mental health and demographic characteristics, but also by environmental conditions.
Researchers said mental health symptoms and environmental exposures may affect sleep through shared biological pathways, including inflammation, stress physiology and disruption of the central nervous system. Those overlapping pathways may help explain why the greatest risk of poor sleep occurred among women with both elevated mental health symptoms and greater environmental exposures.
Environmental predictors included ozone exposure, traffic-related air pollution, toxic metals and a class of flame retardants known as organophosphate esters, reinforcing the role of a person’s surroundings in sleep health during pregnancy.
The researchers found the highest risk among women with both higher-than-average mental health symptom scores and greater environmental exposures, including ozone exposure and living closer to freeways and highways.
The study also found that women living in larger households during pregnancy had a lower risk of poor sleep quality. While household size may contribute to household noise, the researchers noted it also could reflect greater social support, which may help protect sleep during pregnancy.
“Pregnancy is already a time when sleep becomes more difficult for many women,” Breton said. “By understanding how mental health and environmental factors work together, we can begin identifying opportunities to better support mothers during pregnancy.”
