Evidence from Mendelian randomization: increased risk of miscarriage in patients with asthma

Several observational studies have revealed a possible association between asthma and miscarriage. However, inferring causal relationships from observational studies may be fraught with problems like bias, reverse causation, and residual confounding. Therefore, to assess the possible causal effect of asthma on miscarriage, we performed a two-sample Mendelian randomization (MR) analysis.

Asthma (56,167 cases and 352,255 controls) and miscarriage (9,113 cases and 89,340 controls) data from two GWAS of European ancestry were evaluated. Single nucleotide polymorphisms (SNPs) were used as instrumental variables (IVs). The random effect inverse-variance weighted (IVW) Mendelian randomization approach was used as the primary method, and MR-Egger, weighted-median, and MR-PRESSO approaches were replenished as sensitivity analysis to test the robustness of the results.

In total, 70 SNPs were obtained using the SNP criteria. Additionally, the MR study found substantial evidence of the causality between asthma and miscarriage [IVW, OR=1.092; 95% CI=1.017-1.174; p<0.05]. The sensitivity analysis demonstrated the reliability of the MR findings [horizontal pleiotropy (MR-Egger, intercept=-0.0002; Standard error of mean, se=0.006; p=0.975)].

Asthma is a causal risk factor for miscarriage in European populations, according to MR evidence. Our results emphasize the significance of asthma management in reducing the risk of miscarriage in individuals with asthma.