Researchers from the University of California, San Francisco have discovered that women who are diagnosed with sleep disorders during pregnancy, including insomnia and sleep apnea, are at a greater risk of preterm delivery.

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Sleep disorders may increase a woman's likelihood of having a preterm birth, suggest researchers from the University of California, San Francisco.

Lead author Jennifer Felder, Ph.D., a postdoctoral fellow in the Department of Psychiatry at the University of California, San Francisco (UCSF), conducted the study with senior author Aric Prather, Ph.D., an assistant professor of psychiatry, and colleagues. Their findings were published in the journal Obstetrics & Gynecology.

UCSF's research is the first of its kind to explore the effects of insomnia during pregnancy. From a group of nearly 3 million women, 2,265 women diagnosed with a sleep disorder during pregnancy met the inclusion criteria for the study.

The selected participants were matched to controls with no such diagnosis of a sleep disorder, but with the same maternal risk factors for early delivery, such as high blood pressure, smoking during pregnancy, or having a previous preterm birth.

Dr. Felder explains, "This gave us more confidence that our finding of an earlier delivery among women with disordered sleep was truly attributable to the sleep disorder, and not to other differences between women with and without these disorders."

The large sample size allowed Dr. Felder, Prof. Prather, and team to investigate the relationship between various sleep disorders and preterm birth subtypes. For example, the researchers could compare early and late preterm birth, or early induced deliveries and spontaneous preterm labor.

The new study focuses on sleep disorders, such as sleep apnea and insomnia, that might cause significant disruption to sleep, rather than examining the regular sleep changes that tend to occur during pregnancy. The authors say that the true prevalence of these disorders remains unclear because sleep disorders in pregnant women "often go undiagnosed."

Sleep disorders doubled preterm birth risk

The preterm birth rate is around 10 percent in the United States. Identifying women at a higher risk of giving birth early and offering effective treatments may help to prevent preterm birth. Treating sleep disorders during pregnancy may also be a step in the right direction of reducing preterm birth rate.

Their findings showed that preterm birth prevalence - defined as giving birth before 37 weeks of gestation - was 14.6 percent for sleep-disorder affected pregnant women, compared with 10.9 percent for the matched control group.

Furthermore, the chance of early preterm birth before 34 weeks of gestation was more than double for pregnant women who had sleep apnea and almost double for pregnant women diagnosed with insomnia.

Outcomes relating to early preterm birth are important, the authors note, because there is an increased risk of severe complications among early preterm deliveries.

The portion of women in the dataset with a sleep disorder diagnosis was below 1 percent, which was an unexpected result for the team. The researchers suspect that only the most severe cases were identified among the pregnant women.

"The women who had a diagnosis of a sleep disorder recorded in their medical record most likely had more severe presentations. It's likely that the prevalence would be much higher if more women were screened for sleep disorders during pregnancy."

Aric Prather, Ph.D.

Cognitive behavioral therapy (CBT) may be a drug-free option for tackling sleep disorders during pregnancy. Evidence shows that CBT is effective in the general population, and Dr. Felder and collaborators are recruiting participants for the UCSF Research on Expecting Moms and Sleep Therapy (REST) Study to determine whether or not it is effective among pregnant women, and, in turn, whether the therapy will improve birth outcomes.

"What's so exciting about this study is that a sleep disorder is a potentially modifiable risk factor," concludes Dr. Felder.