It is unclear whether treatments for cervical intraepithelial neoplasia
(CIN) increase the subsequent risk of preterm delivery. Most studies have
lacked sufficient sample size, mixed heterogeneous subtypes of preterm delivery,
and failed to control for confounding factors.
To determine whether cervical laser and loop electrosurgical excision
procedure (LEEP) treatments increase risk of preterm delivery and its subtypes.
Design, Setting, and Participants
Retrospective cohort study conducted among women evaluated at a colposcopy
clinic serving Auckland, New Zealand (1988-2000), comparing delivery outcomes
of untreated women (n = 426) and those treated (n = 652) with laser conization,
laser ablation, or LEEP. Record linkage using unique health identifiers identified
women who had subsequent deliveries.
Main Outcome Measures
Total preterm delivery and its subtypes, spontaneous labor and premature
rupture of membranes before 37 weeks' gestation (pPROM).
The overall rate of preterm delivery was 13.8%. The rate of pPROM was
6.2% and the rate of spontaneous preterm delivery was 3.8%. Analyses showed
no significant increase in risk of total preterm delivery (adjusted relative
risk [aRR], 1.1; 95% confidence interval [CI], 0.8-1.5) or spontaneous preterm
delivery (aRR, 1.3; 95% CI, 0.7-2.6) for any treatment. Risk of pPROM was
significantly increased following treatment with laser conization (aRR, 2.7;
95% CI, 1.3-5.6) or LEEP (aRR, 1.9; 95% CI, 1.0-3.8), but not laser ablation
(aRR, 1.1; 95% CI, 0.5-2.4). Moreover, risk of pPROM and total preterm delivery
increased significantly with increasing height of tissue removed from the
cervix in conization. Women in the highest tertile of cone height (≥1.7
cm) had a greater than 3-fold increase in risk of pPROM compared with untreated
women (aRR, 3.6; 95% CI, 1.8-7.5).
LEEP and laser cone treatments were associated with significantly increased
risk of pPROM. Careful consideration should be given to treatment of CIN in
women of reproductive age, especially when treatment might reasonably be delayed
or targeted to high-risk cases.