TUESDAY, Nov. 1 (HealthDay News) -- Pregnant women who have trouble sleeping or experience sleep disruptions during their first or third trimesters are more likely to deliver prematurely, according to a new study.

Sleep problems in the second trimester, however, were not associated with increased chances of preterm birth.

Researchers don't know why there may be a connection between sleep and preterm labor, although hormones or other biological influences may play a role. One possibility is that poor sleep combined with stress may result in inflammation, which could trigger preterm delivery.

The link between sleep and preterm labor was seen even when researchers controlled for other factors that could impact preterm labor, such as other medical conditions.

Researchers said improving the sleep habits of expectant mothers early on may help reduce the risk of preterm births.

The study appears in the Nov. 1 issue of the journal Sleep.

"This supports the growing evidence that poor sleep is an important risk factor for preterm birth," Michele Okun, an assistant professor of psychiatry and psychology at the University of Pittsburgh School of Medicine, said in a journal news release. "It likely occurs in the presence of other risk factors, but sleep can be measured easily and quickly during prenatal visits. Simply by assessing a woman's sleep quality, we may be able to identify a risk early in the pregnancy, when there is time to intervene. The data suggest that beneficial outcomes may be possible through modifications in behavior."

More information

The American College of Obstetricians and Gynecologists provides more information on preterm birth.