Related Experiment Video
Updated: May 17, 2025

Robust Ligature-Induced Model of Murine Periodontitis for the Evaluation of Oral Neutrophils
Published on: January 21, 2020
Unmeasured confounding in meta-analyses of observational studies evaluating maternal periodontitis and adverse birth
May Salama1, Abdullah Al-Taiar1, Denise McKinney2
1Joint School of Public Health, Macon & Joan Brock Virginia Health Sciences at Old Dominion University, Norfolk, VA 23529, USA.
Background:
Maternal periodontitis has been consistently linked to adverse birth outcomes (ABOs). However, a causal relationship is not established due to potential unmeasured confounding factors in observational studies and inconclusive results from randomized controlled trials. This study aimed to assess the impact of unmeasured confounding factors in meta-analyses examining associations between maternal periodontitis and preterm birth (PTB) or low birth weight (LBW).
Methods:
PubMed and MEDLINE, Cochrane, Embase, and Google Scholar were searched for systematic reviews with meta-analyses of observational studies between 2002 and 2023. Systematic reviews with meta-analyses of observational studies were included if either PTB or LBW were the outcome and were published in English. The E-value analogue method was used to evaluate possible unmeasured confounding effects in random effects meta-analyses.
Results:
62 original studies from nine meta-analyses met the inclusion criteria. In relation to the exposure and outcome, the random-effects meta-analysis showed that even with an unmeasured confounder having a relative risk (RR) of 3.00, 80% of cohort studies evaluating PTB and 90% evaluating LBW would have an RR > 2.00.
Conclusions:
Associations between maternal periodontitis and ABOs in observational studies appear robust to unmeasured confounding factors, supporting the hypothesis that maternal periodontitis is causally related to ABOs.
Related Concept Videos
Confounding in Epidemiological Studies
Strategies for Assessing and Addressing Confounding
Confounding can be addressed at both the design phase of a study and through analytical methods after data...
Regression Toward the Mean
Study Designs in Epidemiology
Observational studies are those where the researcher does not intervene but rather observes natural variations. They include cross-sectional, cohort, and...
Bias in Epidemiological Studies

