Association of liver enzyme abnormalities and tobacco exposure with unexplained recurrent spontaneous abortion risk: A case-control study.

ObjectiveUnexplained recurrent spontaneous abortion is a multifactorial condition with an unclear etiology. This study aimed to investigate the relationship between liver function biomarkers and unexplained recurrent spontaneous abortion and explore interactions with tobacco exposure and body mass index.MethodsA retrospective case-control study was conducted on 2126 pregnant women, including 602 with unexplained recurrent spontaneous abortion and 1524 who served as controls. Liver enzyme indicators (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, and alkaline phosphatase) were assessed, and multivariate logistic regression models were applied to analyze their association with unexplained recurrent spontaneous abortion. Interaction analyses were performed to evaluate combined effects of liver enzyme abnormalities, tobacco exposure, and body mass index.ResultsLiver enzyme abnormalities (alanine aminotransferase level >32 U/L or aspartate aminotransferase level >28 U/L) were significantly associated with increased unexplained recurrent spontaneous abortion risk (adjusted odds ratio = 2.15, 95% confidence interval: 1.68-2.76). A significant interaction between alanine aminotransferase elevation and tobacco exposure was observed (p < 0.001). Among non-exposed women, elevated alanine aminotransferase levels were associated with an odds ratio of 1.8 (95% confidence interval: 1.2-2.7), whereas among tobacco-exposed women, the odds ratio was 5.2 (95% confidence interval: 3.1-8.7) (p for interaction <0.001). However, these interaction results warrant cautious interpretation due to the absence of quantitative tobacco exposure metrics. The alanine aminotransferase-body mass index interaction was not significant (p = 0.179).ConclusionsElevated alanine aminotransferase and aspartate aminotransferase levels are independently associated with unexplained recurrent spontaneous abortion, and tobacco exposure significantly strengthened this association. These findings suggest that liver function abnormalities and tobacco exposure are associated with unexplained recurrent spontaneous abortion risk. However, given the limitations associated with tobacco exposure measurement, these findings should be interpreted with caution.