Smoking, alcohol and coffee consumption and pregnancy loss: a Mendelian randomization investigation

To determine the associations of smoking and alcohol and coffee consumption with pregnancy loss.Mendelian randomization study.The UK Biobank study and FinnGen consortium.A total of 60,565 cases with pregnancy loss and 130,687 noncases from UK Biobank and 3,312 cases with pregnancy loss and 64,578 noncases from FinnGen.None.Pregnancy loss.Genetic predisposition to smoking initiation was associated with an increased risk of pregnancy loss in both UK Biobank and FinnGen. The combined odds ratio (OR) was 1.31 (95% confidence interval [CI], 1.25-1.37) for one standard deviation increase in the prevalence of smoking initiation. There were no significant associations of genetically predicted consumption of alcohol (OR, 1.09; 95% CI, 0.93-1.27) or coffee (OR, 0.96; 95% CI, 0.87-1.06) with pregnancy loss.This study on the basis of genetic data suggests the causal potential of the association of smoking but not moderate alcohol and coffee consumption with pregnancy loss.