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The association between cervical excisional procedures, midtrimester cervical length, and preterm birth
Emily S Miller1, William A Grobman1
1Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
American Journal of Obstetrics and Gynecology
|March 11, 2014
Summary
Women who had a prior cervical excisional procedure had shorter cervix lengths. Both the procedure and a short cervix independently increase preterm birth risk, suggesting the procedure
Area of Science:
- Obstetrics and Gynecology
- Maternal-Fetal Medicine
- Reproductive Health
Background:
- Cervical excisional procedures, such as loop electrosurgical excision procedures (LEEP) or cold knife cone biopsies, are performed to treat cervical dysplasia.
- These procedures may affect cervical length and potentially increase the risk of adverse pregnancy outcomes, including preterm birth.
Purpose of the Study:
- To investigate the association between prior cervical excisional procedures and midtrimester cervical length.
- To determine if a shortened cervix mediates the relationship between prior cervical excisional procedures and preterm birth.
Main Methods:
- A cohort study involving 6669 women with singleton pregnancies who underwent routine cervical length assessment between 18 and 24 weeks' gestation.
- Comparison of cervical length and preterm birth rates between women with and without a history of cervical excisional procedures.
- Bivariable and multivariable regression analyses to assess independent risk factors for preterm birth, controlling for cervical length.
Main Results:
- Women with a prior cervical excisional procedure had significantly shorter mean cervical lengths (4.2 cm vs 4.5 cm) and a higher proportion of short cervices (6.5% vs 1.5%).
- Both a short cervix (aOR, 6.19) and a prior cervical excisional procedure (aOR, 1.53) were independently associated with an increased risk of preterm birth.
- Multivariable analysis indicated that the association between prior cervical excisional procedures and preterm birth was not solely explained by cervical length.
Conclusions:
- Prior cervical excisional procedures are associated with shorter midtrimester cervical lengths.
- Both cervical excisional procedures and short cervical length are independent risk factors for preterm birth.
- The increased risk of preterm birth following cervical excisional procedures is not entirely attributable to cervical shortening.
