It may only take one sperm to make a baby, but you need millions of healthy sperm to beat the long odds of your swimmers actually reaching an egg. Any sperm count under 15 million per milliliter is considered low aka oligospermia. Fifteen million sounds like a lot of sperm. But some research believes that amount might not be enough either. A study found men with sperm counts below 40 million sperm per milliliter actually have a steadily decline in their ability to have kids. A semen analysis can tell you about your sperm count.

How are temporal trends in lifestyle factors, including exposure to maternal smoking in utero , associated to semen quality in young men from the general population? Exposure 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. Meta-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. 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. 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.

Sperm are male reproductive cells present in the ejaculate. A doctor can tell someone their sperm count using a test called semen analysis. The average sperm count is between 40 million and million sperm per milliliter. This number can vary between testing centers, with the above range coming from Resolve , a nonprofit fertility association.