Priskorn L, et al. - Researchers investigated the association of temporal trends in lifestyle factors, including exposure to maternal smoking in utero, with semen quality in young men from the general population. Exposure to maternal smoking was observed to be associated with lower sperm counts. However, there appeared no overall increase in sperm counts during the study period despite a decrease in this exposure.

Methods

• Researchers performed a cross-sectional population-based study including ~300 participants per year (total number = 6386) between 1996 and 2016.
• The 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.
• They illustrated temporal trends in semen quality and lifestyle graphically.
• Trends in semen parameters and the impact of prenatal and current lifestyle factors were explored in multiple regression analyses.

Results

• A low semen quality was noted in 35% of the men throughout the study period.
• No persistent temporal trends were observed in semen quality, testicular volume or levels of follicle-stimulating hormone over the 21 years studied.
• Between 2011 and 2016, the men’s alcohol intake was lowest; however, no clear temporal trends were noted regarding BMI, use of medication and smoking.
• Researchers noted that parental age increased, and exposure in utero to maternal smoking decresased from 40% among men investigated in 1996–2000 to 18% among men investigated in 2011–2016.
• Lower sperm counts were observed in association with exposure to maternal smoking, however, no overall increase in sperm counts was noted despite the decrease in this exposure.