Baseline frequency of micronuclei and other nuclear abnormalities in pregnant women: A scoping review and meta-analysis.

Baseline frequency of micronuclei and other nuclear abnormalities in pregnant women: a scoping review and meta-analysis Pregnancy involves physiological and metabolic changes that may influence genomic stability and increase the occurrence of nuclear abnormalities. However, baseline frequency of micronuclei (MN) during pregnancy frequency remains poorly established. This study aimed to review the available evidence on MN frequency in pregnant women and to estimate baseline MN frequency in healthy and high-risk pregnancies through a meta-analysis. A scoping review and a meta-analysis were conducted according to Joanna Briggs Institute recommendations. Searches were performed in PubMed, Scopus, ScienceDirect, and Google Scholar without language or publication date restrictions. Quantitative synthesis was performed using random-effects models with log-transformed values. Sensitivity analyses included Cook's distance, Baujat plots, and leave-one-out analyses. Twenty-six studies involving 2866 participants were included. Most studies were cross-sectional and evaluated environmental exposures, dietary factors, biological/hormonal factors, and maternal diseases or gestational complications. All included studies used the Cytokinesis-Block Micronucleus Assay, whereas only one study additionally applied the Buccal Micronucleus Cytome. The pooled estimated MN frequency was 2.65 (95% CI: 1.45-4.86) in healthy pregnancies and 14.75 (95% CI: 8.76-24.83) in high-risk pregnancies. Subgroup analyses demonstrated higher MN estimates in studies evaluating biological/hormonal factors (5.36; 95% CI: 3.22-8.93) and dietary exposures (4.25; 95% CI: 2.34-7.74). Higher MN frequency was observed only when the high-risk pregnancy group was used as the reference, compared with exposure groups (p < 0.01). These findings suggest that high-risk pregnancies are associated with increased genomic instability and also reinforce the importance of establishing reference estimates for MN frequency in maternal biomonitoring studies.