Paternal Smoking In The Preconception Period Is Associated With An Increased Risk Of Spontaneous Miscarriage In A Dose-Dependent Manner: A Systematic Review And Meta-Analysis

Abstract Study question What is the association between paternal lifestyle ­factors in the preconception period and the risk of spontaneous miscarriage? Summary answer Preconception paternal cigarette smoking is associated with an increased risk of spontaneous miscarriage, while no associations were found with paternal alcohol consumption and obesity. What is known already Although maternal lifestyle risk factors for miscarriage are well-established, studies on potentially contributing paternal factors remain sparse. Recently, a significant association was found between advanced paternal age and spontaneous miscarriage. Biological evidence indicates that smoking, excessive alcohol consumption and obesity may lead to sperm oxidative DNA damage, being a known risk factor for miscarriage. Study design, size, duration Systematic review and meta-analysis. Participants/materials, setting, methods PubMed and Embase databases were searched in August 2020. Paternal factors examined were: cigarette smoking, alcohol consumption and Body Mass Index (BMI). A qualitative risk of bias assessment was performed for all included studies. Meta-analysis was performed if sufficient data was available from studies that controlled for maternal factors. PRISMA guidelines for systematic reviews were followed. Main results and the role of chance The systematic search included 3386 articles of which 11 articles met the inclusion criteria. In a meta-analysis of eight studies, paternal smoking of > 10 cigarettes per day in the preconception period was found to be associated with an increased risk of spontaneous miscarriage, after adjustment for maternal smoking status (1-10 cigarettes per day: 1.01, 95% CI 0.97-1.06; 11-20 cigarettes per day: 1.12, 95% CI 1.08-1.16; >20 cigarettes per day: 1.23, 95% CI 1.17-1.29). Based on five available studies, no clear association was found between paternal alcohol consumption and spontaneous miscarriage. No studies were retrieved that evaluated the association between paternal BMI and spontaneous miscarriage. Limitations, reasons for caution Investigating the relation between paternal lifestyle factors and spontaneous miscarriage is challenging and prone to different forms of bias, especially in retrospective studies. Wider implications of the findings Awareness of the association between heavy paternal smoking in the preconception period and the risk of spontaneous miscarriage should be raised. More well-designed studies are needed to further investigate the effects of other paternal lifestyle factors on the risk of spontaneous miscarriage. Trial registration number not applicable