LEEP increases risk of PTB

Women who undergo loop electrosurgical excision procedure (LEEP) for treatment of cervical intraepithelial neoplasia (CIN) grade 1 and subsequently deliver are at increased risk for preterm birth (PTB), according to a Finnish population-based cohort study published in Acta Obstetrica et Gynecologica Scandinavica.

Using data from the Finnish Hospital Discharge Register and the Medical Birth Register, the researchers identified women diagnosed with CIN 1 between 1997 and 2009 who delivered a child after diagnosis. Cases included 2,006 women with a CIN 1 diagnosis and LEEP, who had 797 deliveries. These women had a mean age of 31.4 years. Three hundred and thirty-four of them were primaparas and 463 were multiparas. The controls were 2,753 women who had a CIN 1 diagnosis but did not receive LEEP; they had 2,220 subsequent deliveries (977 primaparas and 1,243 multiparas), and a mean age of 30.1 years.

All of the women diagnosed with CIN 1 were more likely to be smokers compared to the general population in the Medical Birth Register. The majority (90%) of PTB occurred between 32 and 36 weeks’ gestation. There were no differences between the LEEP and non-LEEP groups in regard to socioeconomic status, marital status, urban/rural location, age of the fetus at birth, or parity. 

Fifty-four (6.7%) of the cases had PTB versus 116 (5.2%) of the controls. Calculating odds ratios (OR), the researchers found an increased risk for PTB associated with CIN 1 and LEEP (OR 1.47, 95% CI 1.05-2.06) but not just for diagnosis of CIN 1 if the LEEP procedure was not performed (OR 0.90, CI 0.71-1.13). 

When compared to the general reference population in the Medical Birth Register, CIN 1 patients who had had LEEP had an elevated risk of PTB (OR 1.45, 95% CI 1.02-1.92). Broken down further, in multiparas who underwent LEEP, the OR rose to 1.59 ( 95% CI 1.09-2.32). Women with CIN 1 who were delivering for the first time had no increase in risk whether they had had LEEP or not. 

There was no increased risk for small-for-gestational age babies in the LEEP and non-LEEP groups compared to the Medical Birth Register. Low birthweight babies were more common in multiparous women who underwent LEEP, but not in other groups. 

LEEP background

LEEP has previously been linked to an increased risk for PTB as well as adverse pregnancy outcomes and low birthweight. An increased cone length with LEEP has also been associated with these risks, but could not be analyzed in this study due to a lack of data in the registry. 

Use of LEEP has declined in recent years in Finland, going from 51% of CIN 1 cases to 32% after an update of Finnish Current Care Guidelines was released in 2007. Many cases of CIN 1 in young women will spontaneously regress within 12 months, and the trend is not to treat them with LEEP unless lesions are still present at 24 months. Based on their data, which confirm previous studies, the authors recommend avoidance of LEEP, especially in younger women with CIN 1.