Average sperm count remains unchanged despite reduction in maternal smoking: results from a large cross-sectional study with annual investigations over 21 years

AbstractSTUDY QUESTIONHow are temporal trends in lifestyle factors, including exposure to maternal smokingin utero, associated to semen quality in young men from the general population?SUMMARY ANSWERExposure to maternal smoking was associated with lower sperm counts but no overall increase in sperm counts was observed during the study period despite a decrease in this exposure.WHAT IS KNOWN ALREADYMeta-analyses suggest a continuous decline in semen quality but few studies have investigated temporal trends in unselected populations recruited and analysed with the same protocol over a long period and none have studied simultaneous trends in lifestyle factors.STUDY DESIGN, SIZE, DURATIONCross-sectional population-based study including ~300 participants per year (total number = 6386) between 1996 and 2016.PARTICIPANTS/MATERIALS, SETTING, METHODSThe study is based on men from the Greater Copenhagen area, Denmark, with a median age of 19 years, and unselected with regard to fertility status and semen quality. The men delivered a semen sample, had a blood sample drawn and a physical examination performed and answered a comprehensive questionnaire, including information on lifestyle and the mother ’s pregnancy. Temporal trends in semen quality and lifestyle were illustrated graphically, and trends in semen parameters and the impact of prenatal and current lifestyle factors were explored in multiple regression analyses.MAIN RESULTS AND THE ROLE OF CHANCEThroughout the study period, ...
Source: Human Reproduction - Category: Reproduction Medicine Source Type: research