Compared with women who didn’t have sleep problems, women with insomnia were 30 per cent more likely to have a premature baby. The odds for women with sleep apnea were 50 per cent higher, the study found. A preterm birth was considered any baby born before the mother was 37 weeks pregnant.
READ MORE: Five signs that you may have sleep apnea
The study found sleep disorders also increased the risk of very premature births, as 5.3 per cent of women with sleep issues delivered their babies at less than 34 weeks of pregnancy, compared to 2.9 per cent for women without a sleep disorder.
“It seems obvious, but strangely this study has not been done before,” lead study author Jennifer Felder said.
“Seeing this relationship is important because we are just starved for interventions that can make a difference.”
A lack of sleep is unlikely to be a direct cause of early births, Felder added. But it could trigger other processes, such as inflammation, that eventually result in prematurity.
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The researchers from the University of California examined more than three million births in California from 2007 to 2012. They focused on 2,172 women who had a sleep disorder diagnosis and compared their birth outcomes to a randomly selected group of 2,172 mothers who were similar in many ways but had no sleep issues.
Overall, almost 15 per cent of women with sleep disorders had a preterm birth, compared with 11 per cent of women without sleep issues.
“It is normal to experience sleep changes during pregnancy — often due to discomfort, pain or frequent trips to the bathroom,” Felder said. “The current study focused on more impairing sleep problems that were severe enough to result in a sleep disorder diagnosis.”
Worldwide, preterm birth is the leading cause of death for children under five years old, the researchers note in the journal Obstetrics and Gynecology.
“What’s so exciting about this study is that a sleep disorder is a potentially modifiable risk factor,” said Felder, who was trained in clinical psychology.
With files from Reuters