5 sperm cells swimming above a female egg cell
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5 Facts About Sperm Cells

In today’s post we’re going to take a closer look at male reproductive health and in particular, the small yet mighty sperm cell. Our five facts about sperm will reveal some unexpected truths about these swift swimmers. We’ll also touch on why knowing about sperm cells is useful for both planning or preventing pregnancy in female fertility too. Read on to find out more!

1. Sperm cells are really, really small….

Have you ever found yourself pondering about the size of these unseen swimmers? Well, sperm cells are actually really tiny. In fact, they are some of the smallest cells in the human body, and measure just 0.005cm. To put that in perspective, scientists need a microscope with 400x magnification to see a sperm cell. This is a big contrast in size to the female egg cell that funnily enough is one of the biggest cells in the human body, and is just about visible with the naked eye… well they do say opposites attract!

2. They may be small, but there are a lot of them!

What sperm cells may lack in size, they certainly make up for in numbers. Providing sperm count is healthy, each male ejaculation contains tens of millions of sperm, with as many as 100 million new cells being produced every single day… That’s quite a lot of sperm, especially when you consider that it only takes a single one to make a baby.

3. The sperm life cycle is 2-3 months 

New sperm cells aren’t just made overnight. In fact, sperm production takes around 64 days on average. Some research suggests that healthy living can have a positive impact on sperm production, although it may take a while before this change is reflected in the health of sperm cells. On the other hand, for those who’ve recently been unwell or have slipped into some unhealthy habits, this might reduce sperm health a couple of months down the line. It’s normal for the health of sperm to fluctuate throughout a man’s lifetime, but those who have concerns about sperm quality should consult with their doctor for guidance.

4. Sperm can live for up to 5 days inside a woman's body

A sperm’s life cycle doesn’t just finish after he does. In fact, sperm cells can live in the female reproductive system for as long as five days after sex. That’s because they’re pretty resilient, and that extra window gives them even more time to swim towards the female egg cell. This egg cell is much more fragile, and after it’s been released from the ovaries, it only lives for a maximum of 24 hours. That means if you’re trying for a baby, the best time to have sex is one or two days before ovulation to allow for the sperm to swim towards the egg before it’s released. Of course, this timing can be a little bit tricky in practice… and sperm survival also depends on ideal conditions, such as fertile cervical mucus

5. Sperm isn’t just found in ejaculate 

While most sperm cells are contained within ejaculate, it is not the only place they hang around. Smaller numbers of sperm cells are also found in pre-ejaculate (pre-cum), which is released before male orgasm. For anyone who’s previously relied on the pull out method this is worth knowing, as this means that even if your partner withdraws in time, there is still a risk from pregnancy from that early sperm release. 

What does Natural Cycles have to do with sperm?

We hope you liked these sperm facts, and that you learned something new! You might be wondering what a women’s health app has to do with sperm in the first place, but sperm survival is integral to how our method works. Natural Cycles is the first FDA cleared birth control app, and it can also be used to plan a pregnancy. In both these modes, our algorithm tracks and predicts ovulation, using body temperature data, to identify the fertile window

With us so far? Great. Now here’s where sperm comes in… since sperm can live in the female reproductive system for up to five days, that means a woman’s fertile window actually opens before ovulation, something our algorithm takes into account. This sperm survival window is important no matter your goal. For couples trying to get pregnant, it increases the chances of conception, and for couples trying to prevent pregnancy, it provides greater accuracy in finding fertile days than traditional calendar-based ways, such as the rhythm method. Want to know more?

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Written By

Jennifer Gray

Jennifer Gray is an award-winning writer with more than five years’ experience covering reproductive topics ranging from birth control to planning pregnancy. She is passionate about providing women with accurate information grounded in science they can use to take charge of their own health - while also dispelling myths that exist within the field of women’s health. She holds a Master of Science from the University of Edinburgh and currently lives in Ireland.

Jack in a suit and tie holding a microphone and giving a presentation.

Scientifically Reviewed

Jack Pearson

Dr. Jack Pearson is a previously HCPC registered Embryologist with a PhD in reproductive medicine. Prior to joining Natural Cycles leading Medical Affairs, he worked for more than 10 years in a clinical setting working at some of the busiest fertility clinics in the UK. Today he spends most of his time working with experts at the world’s leading institutions to carry out important research with the vision to further the field of female health. He earned his PhD from the University of Sheffield specializing in Sperm Metabolism and currently lives in London.

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