How Does Fertilization Work
After sperm arrive, the magic happens in the fallopian tubes. As the fallopian tube pushes the egg towards the uterus, cilia push the sperm towards the egg. Progesterone and estrogen influence this process by increasing the number of cilia and how fast they move .
The egg and surrounding cells produce a chemical that attracts sperm . Sperm may be attracted to the temperature at the ovarian-end of the fallopian tube, which tends to be warmer .
As they travel through the fallopian tubes, sperm gain the ability to fertilize an egg . They undergo two processes: capacitation, where its outer layer is changed, and hyperactivation, which changes the way the spermâs tail moves .
Although itâs come so far and has already changed, the sperm still has work to do: specifically, breaking through the barriers around the egg.
Can You Feel Conception
Not usually. You may notice signs that you’ve ovulated, such as changes in your cervical mucus or basal body temperature. However, most people don’t feel fertilization. You may feel a dull ache or experience light spotting several days after conception. This could be from the fertilized egg implanting in your uterus.
When do you start feeling pregnant?
How long it takes to feel pregnant varies. Some people may start to feel pregnant shortly after conception, while others dont have any pregnancy symptoms for weeks after a positive test.
Take a home pregnancy test if you have any of the above symptoms and think theres a chance youre pregnant. Your healthcare provider can order a blood test to confirm pregnancy.
The Sperm Provides A Centriole For The Zygote
Once fertilized, the is called a . Fertilization is not complete, however, until the two nuclei have come together and combined their chromosomes into a single . In fertilized mammalian eggs, the two pronuclei do not fuse directly as they do in many other species. They approach each other but remain distinct until after the of each pronucleus has broken down in preparation for the ‘s first mitotic division .
The coming together of the sperm and egg pronuclei after mammalian fertilization. The pronuclei migrate toward the center of the egg. When they come together, their nuclear envelopes interdigitate. The centrosome replicates, the nuclear envelopes break
In most animals, including humans, the sperm contributes more than to the . It also donates a âan that is lacking in unfertilized human eggs. The sperm centriole enters the along with the sperm and tail and a forms around it. In humans, it replicates and helps organize the assembly of the first in the zygote . This explains why multipolar or extra mitotic spindles form in cases of polyspermy, where several sperm contribute their centrioles to the egg.
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What Is Gestational Age
The term gestational age basically means how far along into a pregnancy you are. Gestational age is counted by starting with the first day of your last menstrual period .
Gestational age can be kind of confusing, since it measures pregnancy from your last period about 3-4 weeks BEFORE youre actually pregnant. Common knowledge about pregnancy says it lasts 9 months, and its true that youre usually pregnant for about 9 months. But the way pregnancy is measured makes it a little longer. A typical full-term pregnancy ranges from 38-42 weeks LMP around 10 months.
Many people cant remember the exact date of their last menstrual period thats totally okay. Your nurse or doctor can find out the gestational age using an ultrasound.
Can You Feel Yourself Getting Pregnant

Some women may notice symptoms as early as 5 DPO, although they wont know for certain that they are pregnant until much later. Early signs and symptoms include implantation bleeding or cramps, which can occur 56 days after the sperm fertilizes the egg. Other early symptoms include breast tenderness and mood changes.
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How Does Conception Work With Ivf
Conception still works the same way sperm must fertilize an egg. However, with in vitro fertilization , sperm fertilizes an egg in a lab. An egg, either from the intended parent or a donor, is mixed with sperm from a parent or donor. Conception happens when sperm fertilizes the egg.
Once conception occurs, your provider places the created embryo inside the uterus that will carry the pregnancy for implantation.
What Barriers Do Spermatozoa Have To Cross
Some obstacles, or barriers, encountered by sperm are as follows:
- Vaginal pH
However, it is not all difficulties in the journey of the sperm. The egg tries to pave the way for the sperm by releasing molecules and sending signals. The fallopian tubes and uterus exert a suction force through rhythmic contractions and the cervical mucus becomes less dense allowing the sperm to swim better.
For its part, the seminal fluid that accompanies the sperm neutralizes the pH and provides sugars to the sperm. This fluid also serves as a protective shield against the woman´s white blood cells.
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How Many Hours Does Ovulation Last
Understanding your menstrual cycle and how ovulation works is key to family planning. Ovulation occurs once a month and lasts for about 24 hours. The egg will die if its not fertilized within 12 to 24 hours. With this information, you can start tracking your fertile days and improve your chances of conceiving.
Heres How Long It Takes Sperm To Reach The Egg After Sex
We all know that in order to get pregnant, a sperm needs to fertilize an egg. It sounds simple enough, but theres more to it than you might think.
If you have unprotected sex in your fertile window, you might assume that youre guaranteed to get pregnant. In fact, theres only a 10% to 33% chance of getting pregnant , which shows there are a fair few hurdles standing in the way.
If youre keen to clue yourself up on all things conception, you probably want to know the details: How long does it actually take for sperm to reach the egg after sex? What does the journey involve? And how many sperm can you realistically expect to make it all the way?
To answer all these burning sex ed questions , we dug into the research and spoke to fertility expert, reproductive endocrinologist, and Flo Medical Board member Dr. Tiffany Jones for a fascinating glimpse at what really goes on inside after sex.
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Implantation: What Happens After The Egg Is Fertilized
It takes about 6-12 days for the fertilized egg to travel to the uterus and attach to the uterus in a process known as implantation . The egg is pushed back towards the uterus by the cilia . The egg must attach to the uterus to become a viable pregnancy.
While traveling to the uterus, the egg has been dividing and forming a few different structures.
Once itâs big enough *and* in the uterus, the egg transitions from being known as a zygote to being called a blastocyst .
What Happens If Sperm Reaches An Egg That Is Already Fertilized
Remember those pictures of fertilized eggs you saw in sex ed class at school? More often than not, the fertilized egg was surrounded by multiple, competitive sperm that looked like they might be on the brink of entering the egg at any moment. So the question is, can sperm enter an egg thats already been fertilized?
Quite simply, the answer is no, says Dr. Jones. Our eggs have a shell, called the zona pellucida, she explains. Once the sperm breaks through, the shell of the egg is cemented so no other sperm can come in.
However, while a sperm cant enter an egg thats already been fertilized, it is possible for more than one sperm to enter the egg at the exact same time. This is very rare double fertilization accounts for around 1% of all fertilizations. Unfortunately, in this instance, there is usually too much genetic material for the egg to fertilize normally, and so generally, it doesnt survive.
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What Happens To Sperm Inside A Woman
Once the sperm enters the reproductive system, it can take about 30-45 minutes to reach the egg. For this, it is important to have a healthy sperm which has the right kind of motility to reach the egg and fertilize it.
Once inside the body of a woman, a healthy sperm can live up to 2-5 days. Once the sperm reaches the released egg, it does not mean that it is capable of fertilizing it immediately. The sperm will then undergo a process called capacitation in the reproductive tract. This process will take about 10 hours.
It is safe to say that the fertilization time is appropriately about 24 hours. When the sperm penetrates the egg, the surface of the egg changes and blocks the entry of other sperms. The genetic makeup of the baby is complete at the moment of fertilization.
The fertilized egg then starts dividing frequently into many cells. Once the fertilization process is over, the fertilized egg will travel through the fallopian tube, enters the uterus in another 3-4 days, and attaches itself to the lining of the uterus, and slowly grow to become the baby.
How Soon After Unprotected Can I Test For Pregnancy

You can carry out most pregnancy tests from the first day of a missed period. If you dont know when your next period is due, do the test at least 21 days after you last had unprotected sex. Some very sensitive pregnancy tests can be used even before you miss a period, from as early as 8 days after conception.
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How Long Does It Take Sperm To Reach The Egg
There is no set time, since the spermatozoa with the best quality, that is, with great ability to overcome obstacles and great strength of movement, will be able to reach the egg in just half an hour. However, there will be others that will need about two days to cross the entire female reproductive tract.
How Long Does It Take Sperm To Reach The Egg After Iui
People considering fertility treatments often focus on in vitro fertilization . IVF can be highly successful for the right person, but its also expensive. Intrauterine insemination offers a success rate of 10-20% per cycle. This makes it a highly effective treatment, and one that is much more affordable than IVF. For couples with unexplained infertility and some other fertility issues, its a great option. Moreover, because its more affordable, most families can pursue several cycles of IUI, increasing the odds of a successful pregnancy without breaking the budget. If youve spent some time trying to get pregnant, you already know about the two-week wait. Youve probably spent quite a bit of time reading about pregnancy symptoms, taking early pregnancy tests, or posting your symptoms on message boards. An IUI procedure begins a new type of two-week wait — but this time with a much higher probability of success than trying to get pregnant the old-fashioned way. If youve just had an IUI, you probably wonder how long till the sperm fertilizes the egg, and how long youll have to wait for signs of pregnancy. Heres what you need to know.
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How Long Does Implantation take after IUI?
Implantation: The Moment of Pregnancy
. Sometimes implantation failure happens because of an ongoing condition such as: Uterine growths such as fibroids
. Endometriosis, which can strangle the egg or make implantation difficult
. Sperm issues
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Question: How Long Does A Sperm Take To Fertilize An Egg
It takes about 24 hours for a sperm cell to fertilize an egg. When the sperm penetrates the egg, the surface of the egg changes so that no other sperm can enter. At the moment of fertilization, the babys genetic makeup is complete, including whether its a boy or girl.
Final Stage Of The Spermatozoon: Acrosome Reaction
As mentioned above, when the most able sperm has reached the egg, the acrosome reaction takes place. This is the release of the contents of the acrosome, which is composed of a series of enzymes. The purpose of this enzymatic release is to weaken the zona pellucida of the ovum and facilitate penetration.
The acrosome is a structure located in the head of the sperm. It serves as a reservoir for enzymes and other substances that the sperm needs to pass through the zona pellucida.
This reaction “wakes up” the egg, which releases cortical granules, organelles that prevent any other sperm from penetrating. It is as if the ovum plants a flag indicating to the rest of the spermatozoa around it that it has already been conquered by the winning spermatozoa and, therefore, that the doors of its kingdom are closed.
Once the sperm penetrates the oocyte, their two nuclei fuse. This is what we know as fertilization. If you want to know the details about how the sperm enters the egg and how the new being is formed, you can read this article: The steps of fertilization in humans.
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How Can You Prevent Sperm From Reaching And Fertilizing The Egg After Unprotected Sex If Youre Trying To Avoid Getting Pregnant
If youve had unprotected sex and youre trying to avoid getting pregnant, emergency contraception such as the morning after pill can either stop or delay your egg from being released, meaning it cant be fertilized. If your egg has already been released, emergency contraception could also work to prevent fertilization or implantation from occurring.
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How Long Does Fertilization Take
Fertilization can only happen if a sperm and an egg meet. Once its released from the ovary, an egg can only live for about 12 to 24 hours. Sperm, on the other hand, can live for 3 to 5 days inside your body.
There is a window of time known as the fertile window where pregnancy is possible during each month. An egg can be fertilized if you have sex anywhere from approximately five days before ovulation until the day of ovulation. The best chances of pregnancy are when sperm are present in the fallopian tube, ready to meet a just-ovulated egg.
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How The Uterus Interacts With Sperm
Sperm triggers an immune response when it enters the uterus . Once sperm enter, the number of white blood cells increases, and they begin to attack the dying sperm, though itâs possible they may also attack healthy sperm too .
Also, sperm may end up going up the wrong fallopian tube. The vast majority of the time, a person only releases one egg from one ovary. That means that only one of the two fallopian tubes will have eggs, and some sperm will have gotten it wrong.
Do U Think Im Pregnant

The most common early signs and symptoms of pregnancy might include: Missed period. If youre in your childbearing years and a week or more has passed without the start of an expected menstrual cycle, you might be pregnant. However, this symptom can be misleading if you have an irregular menstrual cycle.
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How Many Sperm Make It To The Egg
To answer this question, we will split the answer into various figures, each one corresponding to a stage in the journey:
- Once there, out of the 2 million sperm entering the cervix, only about 1 million are able to make it to the uterus.
- Out of the 1 million that enter the uterus, only 10,000 are able to travel to the top of this organ.
- Out of the 10,000 that survive at this point, only half of them travel in the right direction, that is, toward the egg cell.
- Out of the approximately 5,000 sperm that enter the utero-tubal junction, about 1,000 get inside the Fallopian tube.
- Finally, out of the 1,000 that enter the tube, it is estimated that only 200 make it to the egg.
However, in the end, only 1 sperm out of the 200 that reach the egg is able to penetrate and fertilize it.
Need Help Getting Pregnant
Whether it’s a fertility check up or fertility advice and assisted conception treatment, Complete Fertility Centre can help you on your fertility journey to have the best chance of a healthy baby. Book an appointment using our from below, or come along to one of our free events for people thinking about starting fertility treatment.
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How Long After Conception Will My Pregnancy Test Be Positive
It can take between 11 and 14 days after conception to get a positive pregnancy test. At-home pregnancy tests check for human chorionic gonadotropin , a hormone released by the placenta. Your pee must have enough hCG to get a positive pregnancy test. However, your healthcare provider can check for hCG in your blood sooner around 10 days after conception.
A note from Cleveland Clinic
Conception is when sperm fertilizes an egg. Its one of the many critical steps in getting pregnant. Conceiving a child is a complex process dependent on lots of factors. Being unable to conceive is a common problem, and there are lots of resources available to help you. Contact your healthcare provider if youre struggling with conceiving. They can explain the process and identify any issues preventing conception and pregnancy.
Last reviewed by a Cleveland Clinic medical professional on 09/06/2022.
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