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Sleep disorders increase risk for preterm birth

Women diagnosed with insomnia or sleep apnea during pregnancy have significantly increased odds of giving birth before 37 weeks gestation, according to new findings published in Obstetrics & Gynecology.

“Preterm birth is the leading cause of death in children younger than 5 years old worldwide and is associated with lifelong morbidity,” Jennifer N. Felder, PhD, from the University of California, San Francisco, and colleagues wrote. “Recent vital statistics signal an upward trend in preterm birth rates in the United States. Sleep disturbance may be a novel risk factor that is identifiable and modifiable, but there is a paucity of research examining sleep disorders and risk of preterm birth.”

Felder and colleagues conducted the first study to investigate whether a sleep disorder diagnosis affects the risk for preterm birth, which was defined as delivery before 37 weeks gestation. They examined the risk by gestational age, preterm birth type and specific sleep disorder, such as insomnia, sleep apnea and movement disorder. Women with a sleep disorder but without mental illness during pregnancy who gave birth to singleton neonates between 20 and 44 weeks of gestation without chromosomal abnormalities or major structural birth defects were included in the analysis. The researchers used the International Classification of Diseases, 9^th Revision, Clinical Modification diagnostic code to define sleep disorders. Gestational age (less than 34 weeks, 34-36 weeks and less than 37 weeks of gestation) and type (spontaneous or indicated) were used to assess odds of preterm birth.

Participants were matched one-to-one to controls without a sleep disorder, but with identical maternal risk factors for preterm birth, including previous preterm birth, smoking during pregnancy or hypertension.

“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,” Felder said in a press release.

From a large cohort of approximately 3 million women in California, the researchers identified 2,265 participants with a sleep disorder.

“The women who had a diagnosis of a sleep disorder recorded in their medical record most likely had more severe presentations,” Aric Prather, PhD, senior author of the study from the University of California, said in the release. “It’s likely that the prevalence would be much higher if more women were screened for sleep disorders during pregnancy.”

The researchers found that the prevalence of preterm birth was higher in women with a sleep disorder diagnosis during pregnancy than in those without (14.6% vs. 10.9%). The odds of preterm birth for insomnia and sleep apnea were 1.3 (95% CI, 1.0-1.7; P = .023; 14.1%) and 1.5 (95% CI, 1.2-1.8; P < .001; 15.5%), respectively. Women with sleep apnea had more than double the odds of early preterm birth (before 34 weeks) and women with insomnia had nearly twice the risk compared with those who did not have a sleep disorder. The researchers observed a variation in risk by gestational age and preterm birth type. Sleep-related movement disorders or other sleep disorders did not significantly increase the odds of preterm birth.

“What’s so exciting about this study is that a sleep disorder is a potentially modifiable risk factor,” Felder said in the release.

These data indicate that the preterm rate could be reduced by treating sleep disorders during pregnancy, according to Felder and colleagues.

“Considering the high prevalence of sleep disorders during pregnancy and availability of evidence-based nonpharmacologic interventions, current findings suggest that screening for severe presentations would be prudent,” they concluded.

“More work is urgently needed to test whether this is a causal relationship, identify biological mechanisms, and test the efficacy of interventions for sleep disorders during pregnancy and the effect on preterm birth,” they added.

Since many pregnant women often go undiagnosed for sleep disorders, the exact prevalence is unknown, the researchers noted. – by Alaina Tedesco

Disclosure: Prather reports being a paid consultant for Posit Science.