The high concentration of bacteria in fetal membranes may be the major reason why pregnant woman experience "water breaking" prematurely, according to a recent study HealthDay reported.

Researchers at Duke University found that close to one-third of early births are associated with the "premature rupture of fetal membranes." They discovered an association between the weakening of the membrane and a high presence of bacteria, HealthDay reported.

"Complications of preterm births can have long-term health effects for both mothers and children," Amy P. Murtha, study author and associate professor of obstetrics and gynecology at Duke University School of Medicine, said in a statement. "Our research focuses on why the fetal membranes, or water sac, break early in some women, with the overall goal of better understanding the mechanisms of preterm membrane rupture."

For the study, the researchers analyzed amniotic sacs from 48 women after they gave birth.

Researchers said they don't know if the relationship between early births and bacteria in the fetal membrane is a causal one.

"We still know little about changes occurring within the fetal membrane in the presence of bacteria, but our data suggest the chorion and its thinning may be the battleground for these changes," Murtha said.

Researchers said further analysis is needed to determine whether the presence of high levels of bacteria is a cause or result of fetal membrane weakening, the investigators said.

They are currently investigating whether certain types of bacteria may increase the risk of premature rupture of fetal membranes, which could lead to the development of preventive treatments.

"For instance, if we think that certain bacteria are associated with premature rupturing of the membranes, we can screen for this bacteria early in pregnancy," Murtha said.

She said treating the affected women with antibiotics might reduce their risk for this problem.