Maternal marijuana use during pregnancy is not an independent risk factor for adverse neonatal outcomes after adjusting for confounding factors. Thus, the association between maternal marijuana use and adverse outcomes appears attributable to concomitant tobacco use and other confounding factors.
Objective
To assess whether loop electrosurgical excision procedure (LEEP) increases the risk for preterm birth before 37 weeks of gestation, and clarify whether the increased risk for preterm birth is attributable to the procedure itself or to risk factors associated with cervical dysplasia.
Data Sources
Two authors performed a search of the relevant data through February 2013 utilizing PubMed, Embase, Scopus, CENTRAL, and ClinicalTrials.gov.
Methods of Study Selection
We included observational studies that compared rates of preterm birth in women with prior LEEP to women with no history of cervical excision. Nineteen out of 559 identified studies met selection criteria.
Tabulation, Integration, and Results
We compared women with a history of LEEP to two unexposed groups without a history of cervical excision: 1) women with unknown or no history of cervical dysplasia; and 2) women with history of cervical dysplasia, but no cervical excision. The primary outcome was preterm birth before 37 weeks. Secondary outcomes were preterm birth before 34 weeks, spontaneous preterm birth, preterm premature rupture of membranes, and perinatal mortality. DerSimonian-Laird random effects models were used. We assessed heterogeneity between studies using the Q and I2 tests. Stratified analyses and meta-regression were performed to assess confounding. Nineteen studies were included, with a total of 6,589 patients with history of LEEP, and 1,415,015 without. Overall, LEEP was associated with an increased risk of preterm birth before 37 weeks (pooled RR 1.61, 95% CI 1.35–1.92). However, no increased risk was found when women with a history of LEEP were compared to women with a history cervical dysplasia but no cervical excision (pooled RR 1.08, 95% CI 0.88–1.33).
Conclusion
Women with history of LEEP have similar risk of preterm birth when compared to women with prior dysplasia, but no cervical excision. Common risk factors for both preterm birth and dysplasia likely explain findings of association between LEEP and preterm birth, but LEEP itself may not be an independent risk factor for preterm birth.
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