Last Updated: 2003-08-04 13:14:17 -0400 (Reuters Health)

NEW YORK (Reuters Health) - The likelihood of delivering a preterm baby is increased considerably if the mother has a vaginal bacterial infection during pregnancy. The risk is especially high if bacterial vaginosis, as the condition is called, is present during the first 20 weeks of pregnancy.

The link between vaginosis and preterm delivery has been "confirmed repeatedly and consistently," Dr. Harald Leitich and associates at the University of Vienna in Austria write in the American Journal of Obstetrics and Gynecology. To examine the problem in more detail, the scientists re-analyzed 18 studies on the topic, involving all together over 20,000 women.

As expected, the full analysis showed that vaginosis more than doubled the chances of a pregnant woman delivering her baby before 37 weeks.

When the researchers looked at cases in which vaginosis was present before 20 weeks, the odds of a preterm delivery were 4-fold higher. With vaginosis occurring before 16 weeks, the risk increased 8-fold.

The team also uncovered another risk: bacterial vaginosis increased the risk of spontaneous abortion nearly 10-fold. This "appears to have received little attention so far, but clearly deserves attention," Dr. Leitich and colleagues write.

Meanwhile, what to do about the problem is unclear. "Strategies to screen for and treat bacterial vaginosis in pregnancy remain controversial," the team acknowledges.