While you lot release but a single egg each month, your partner releases millions of sperm in a single ejaculation — all with an eye on that unmarried prize. But only ane of those sperm volition be crowned the victor, and the odds are stacked against fertilization.

Luckily, egg and sperm have developed some pretty cool tricks to requite themselves a fighting chance. Read on to find out how fertilization actually works.

What is fertilization?

fertilization and implantation medical illustration

Fertilization is when a human being's sperm combines with a woman'south egg to form a single cell. It'south one of the get-go steps toward pregnancy, but there are more hurdles to cantankerous.

Where does fertilization occur?

Some people think fertilization happens in the uterus, since that's where the babe develops. Yet, fertilization actually occurs in the fallopian tubes.

Each sperm has a single goal: to encounter up with the egg. To reach the target, though, a sperm cell has to get on a lengthy and strenuous journey.

First, information technology must make its way from the vagina to the cervix, and so it has to swim through the uterus to the fallopian tubes. Once there, if the sperm is the lucky one, it volition penetrate the egg and fertilize it. The newly fertilized egg (at present called a zygote) volition brand its way from the fallopian tubes to the uterus. There, it will hopefully implant in the uterine wall and grow into a baby.

Most of the time, implantation occurs in the uterus as it should. However, sometimes the fertilized egg implants and grows somewhere outside of the uterus. This is chosen an ectopic pregnancy.

Usually, an ectopic pregnancy occurs in a fallopian tube (which is why you may have heard of information technology being called a tubal pregnancy), but information technology may as well happen in an ovary, the cervix or even the abdomen.

Continue Reading Below

Read This Next

Since none of those areas has the correct tissue or the infinite to conform a growing pregnancy, an ectopic pregnancy is not a viable pregnancy.

When does fertilization occur?

For fertilization to happen, the timing and conditions must be but right. The fertilization process can only occur during a fairly small window within just a few days of ovulation (a few days before upwards until a twenty-four hour period afterward you ovulate).

Even if a sperm does brand its way to the fallopian tube, that doesn't mean it volition definitely be able to fertilize the egg. Aside from diverse fertility-related problems that can hamper the process, the timing may be off, meaning the sperm arrived too early or too tardily to come across up with the egg. Or the sperm may have entered the wrong fallopian tube (an egg is usually nowadays in only one of the fallopian tubes in any given month).

How long does it accept for a sperm to fertilize an egg?

Contrary to what many people believe, fertilization doesn't occur immediately later on sex activity. The fastest sperm can reach the egg in as petty as an hour after, but the entire fertilization process tin can have several hours. After ejaculation, the sperm are gearing up for that long journey.

For about a half an hr after sex, the semen coagulates in a woman's vagina, forming a physical barrier that prevents the sperm from wandering very far in the wrong direction. This protection disappears within 30 minutes, when the semen reliquefies.

Whatsoever sperm that haven't made information technology up through the cervix by then are eliminated from the running. The vagina is very acidic and quickly destroys any errant cells, including sperm.

The sperm that arrive to the adjacent stride — the cervical culvert — spend time going through biochemical changes, picking up the tail-thrashing speed that's required for them to swim their way through the uterus and fallopian tubes to discover their target.

The cervical canal is a much more welcoming environment, where the mucus is specially designed to ship sperm efficiently when you're near fertile.

As yous approach ovulation, your suddenly copious mucus becomes stretchy, clear and thin (that's ane of the reasons why observing information technology is such an constructive method of determining your ovulation time). The changes happen on a microscopic level every bit well, as strings of molecules line upwards like train tracks so that sperm can hop on and ride to their destination.

The sperm that practise reach the egg all the same have their work cut out for them. The race is on to be the first one to plough through the hard outer layer of the egg.

And there'due south enough of competition. Hundreds of sperm will surroundings the egg during the frantic battle to the cease, all trying to penetrate the egg's membrane to reach the cytoplasm, where the sperm volition then release its own genetic contribution.

As soon equally ane lucky sperm cell succeeds in penetrating the egg, the egg immediately undergoes a chemical reaction that prevents other sperm cells from following arrange. So the chromosomes carried past the sperm and egg come together, and the egg is officially fertilized.

Can you lot feel when an egg gets fertilized?

Yous won't feel when an egg gets fertilized. You also won't feel pregnant after two or 3 days. But some women tin feel implantation, the process in which the fertilized egg travels down the fallopian tube and buries itself deep within the wall of the uterus.

This happens nigh eight to 9 days after fertilization, though information technology can happen earlier or afterward, depending. Symptoms of implantation may include abdominal cramps and calorie-free bleeding. Whether y'all feel annihilation or not, implantation is the moment that fertilization gives way to pregnancy!

How long can sperm live inside you to get pregnant?

Sperm can survive inside the female reproductive tract for about 72 hours. And, in some cases, the sperm tin can alive for up to v days. Merely the lifespan of an egg is much shorter. The egg lives for merely 12 to 24 hours later ovulation.

If sperm aren't hanging effectually by time the egg makes it to the fallopian tube (or if they don't reach the destination shortly subsequently the egg arrives), the body reabsorbs the egg, and the window of opportunity for conception that month closes.

As you lot've no doubt learned by now, the road to fertilization is a bumpy i, with enough of twists and turns. Information technology takes a lot of work, the right conditions and perfect timing for the egg and sperm to come across upwards and produce that baby you're hoping for. Merely one time they practice, yous've embarked on your own amazing journey: the journey of parenthood.