If pregnancy occurs too soon after a woman undergoes a common minor surgery to the cervix, there appears to be a heightened chance of preterm birth, researchers report in the journal Obstetrics and Gynecology.

In the procedure, called conization, a cone-shaped or cylindrical wedge is removed from the cervix with a scalpel, laser or electrical loop. The procedure can be used to diagnose and, in some cases, treat early cancerous growths.

Most evidence supports an increase risk of preterm birth after conization procedures for cervical abnormalities, Dr. Katherine P. Himes, from the University of Pittsburgh School of Medicine, told Reuters Health.

To determine whether these procedures might influence preterm birth, the researchers studied data for 114 women who gave birth at their institution and who previously had undergone a conization procedure. These findings were compared with those from 962 women who did not undergo the procedure.

Overall, conization was not associated with preterm birth. However, women who did have a premature infant became pregnant much sooner after conization than did women who had a full-term baby. The findings suggest that a wait of at least 3 months reduces the risk of having a preterm infant.

The team notes that the underlying reason for the association is unclear, but they suggest that the “structural integrity of the cervix may be diminished immediately after a cone procedure, limiting the ability of the cervix to support a pregnancy.”

Himes concluded: “Our findings suggest that conceiving within 3 months of a cone procedure may be a modifiable risk factor for preterm delivery. Thus, encouraging patients to delay conception outside of this high-risk window could be part of patient counseling after cone procedures.”

SOURCE: Obstetrics and Gynecology, February 2007.