Rocker Pat Benatar once famously sang, "Love is a Battlefield." She probably had no idea how right she was when it comes to getting pregnant. The odds of a male sperm surviving long enough to reach and fertilize an egg are almost astronomical.
True, it only takes a single determined sperm to do the trick. But, on average, a man ejaculates a teaspoonful of semen, containing roughly 100 to 300 million sperm. Fewer than 100,000 make their way through a woman's cervix, and only a couple hundred will survive the journey up into the fallopian tubes [source: Regan]. All of this proves the importance of having strong, mobile sperm.
Perhaps the biggest difference in the sperm/egg equation is that females are born with all the eggs they will ever have (roughly 3 million, only about 400,000 of which survive to puberty and about 400 of which are eventually released) [source: Regan].
Males, on the other hand, start producing sperm at puberty and, avoiding any complications, will continue throughout their lives (though sperm production and mobility decrease with age). That's important, since the average lifespan of a sperm cell is only 72 days to three months. When called to action, you want not only an adequate supply, but also a vigorous supply of healthy sperm.
Our first stop? Go see your doctor.