Women’s Health: Infection in first pregnancy doubles the risk for repeat problem

For unknown reasons, some women are more susceptible than others to bacterial infection in the uterus

Women who have an infection in the uterus during their first pregnancy are at increased risk for a recurrence in a subsequent pregnancy. Although the risk is low, there is nothing doctors can do to prevent the problem, according to researchers.

This type of infection, known as chorioamnionitis, involves the chorion and amnion (the membranes that surround the fetus) and the amniotic fluid (in which the fetus floats). In most cases, the baby must be delivered as soon as possible. The condition is caused by a bacterial infection that usually starts in the vagina, anus or rectum and moves up into the uterus.

Dr. Vanessa Laibl of the department of obstetrics and gynecology at the University of Texas Southwestern Medical Center in Dallas studied more than 23,000 women who delivered their first two babies between January 1988 and May 2005. In each case, the women were pregnant with a single child and delivered vaginally.

During their first pregnancy, 10 per cent of the women developed chorioamnionitis. Compared with women who were not infected, these women were significantly more likely to have known risk factors for chorioamnionitis, such as prolonged labour, induced labour, rupture of membranes more than 24 hours before delivery, and the use of an internal fetal monitor. The study was designed to investigate whether some women get chorioamnionitis more often than others, even when taking these risk factors into account.

Data on second pregnancies indicated that chorioamnionitis was significantly more common in the women who had also been affected in their first pregnancy. In this group, six per cent had chorioamnionitis in their second pregnancy, compared with two per cent of the women who had not had an infection in their first pregnancy. After adjusting for other risk factors, Laibl found that women who had one infection were almost twice as likely as unaffected women to have chorioamnionitis in a subsequent pregnancy.

Laibl says she hopes these findings spark research into why some women are more susceptible to chorioamnionitis than others, but she adds the findings should not affect clinical practice except perhaps to let women with a previous infection know they may have an increased risk. “I would probably tell them that, from the study that I did, they’re probably twice as likely — but that the risk is still low. There’s nothing that we would do differently for her other than just to give her the good care she should receive regardless.”