Pregnant mums: if you have insomnia, here's how it could impact your due date.

A US study has found that women who suffer from sleep disorders during pregnancy appear to be more likely to experience premature delivery.

The researchers from University of California San Francisco found the prevalence of preterm birth — that is prior to 37 weeks’ gestation — was 14.6 percent for women diagnosed with a sleep disorder during pregnancy, compared to 10.9 percent for women who were not.

The odds of early preterm birth (before 34 weeks), meanwhile, was more than double for women diagnosed with sleep apnea during pregnancy and nearly double for women with insomnia.

“What’s so exciting about this study is that a sleep disorder is a potentially modifiable risk factor,” said lead author Jennifer Felder, a postdoctoral fellow in the UCSF Department of Psychiatry.

The study, published in Obstetrics & Gynecology, looked at data from more than three million Californian births, and compared 2,265 women who had been given a sleep disorder diagnosis during pregnancy to an equal number who had not.

These two groups had otherwise identical maternal risk factors for preterm birth, for example, previous preterm birth, smoking during pregnancy or high blood pressure.

“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,” said Felder.

So you’re pregnant. Now what? (Post continues below.)

The study authors stressed that the results aren’t related to the normal sleep changes women experience during pregnancy.

While those can usually be attributed to discomfort, pain or frequent trips to the bathroom, this study focused on sleep problems that were severe enough to result in a sleep disorder diagnosis.

However, given that these constituted well below one per cent of the data-set, they suspect that only the most serious cases were identified.

“More severe sleep disorders are often underdiagnosed, because poor sleep is common during pregnancy,” Felder told The New York Times. “But for women having sleep problems that are severe, impairing and distressing, it’s important to talk to their health care providers.”