Conception occurs when the

Fertilization, Process & When It Happens

How does conception occur?

Conception (or fertilization) is when sperm and an egg join together. It’s one of the many steps that happen to create a pregnancy.

Conception is closely related to a person’s menstrual cycle. A menstrual cycle describes the sequence of events that occur within your body as it prepares for the possibility of pregnancy each month. Women or people assigned female at birth (AFAB) ovulate during their menstrual cycle. Ovulation is when your ovary releases an egg for fertilization. Tiny finger-like structures called fimbriae help guide the egg through your fallopian tubes towards your uterus. During this journey through your fallopian tubes, an egg can be fertilized by sperm.

Sperm production begins in the testicles of men or people assigned male at birth (AMAB). During ejaculation, millions of sperm cells are set free with the sole purpose of finding an egg to fertilize. When you have unprotected sex, sperm cells swim up through your vagina and into your fallopian tubes. Millions of sperm battle to reach and penetrate the egg, but only one breaks through the egg's outer layer to fertilize it. If sperm doesn't fertilize an egg, the egg dissolves.

If a sperm is successful on its quest to fertilize an egg, the now fertilized egg (called a zygote) continues to move down your fallopian tube, dividing into two cells, then four cells, then more cells. About a week after the sperm has fertilized the egg, the zygote has traveled to your uterus. It's now a growing cluster of about 100 cells called a blastocyst.

The blastocyst then attaches itself to the lining of your uterus (the endometrium). This attachment process is called implantation. However, just because conception occurs doesn't mean implantation will. Sometimes implantation doesn't happen, and you pass the fertilized egg in your next menstrual period.

If implantation happens, the cells continue to divide — some cells develop into your baby and others form the placenta. You begin to release hormones that tell your body a baby is growing inside your uterus. These hormones also signal the uterus to maintain its lining rather than shed it. This means you won't get your menstrual period, which may be the first way you know you’re pregnant.

Timeline of getting pregnant

You calculate your menstrual cycle from the first day of menstrual bleeding to the start of the next first day of menstrual bleeding. Most menstrual cycles are around 28 days long. The exact time you ovulate varies depending on how long your menstrual cycle is.

The process of getting pregnant in a 28-day menstrual cycle is:

Day one: First day of your period.
Around day 14: Ovulation occurs.
Within 24 hours of ovulation: Sperm fertilizes an egg (conception occurs).
About six days after fertilization: The fertilized egg implants into your uterine lining.
Around day 21: If conception and implantation occurred during this menstrual cycle, you're pregnant. However, getting a positive pregnancy test may take another five to seven days.

Conception and a positive pregnancy test

After conception, a fertilized egg travels through your fallopian tubes to your uterus. The fertilized egg (called an embryo) implants (attaches) into the wall of your uterus. This triggers the placenta to form. Your placenta begins producing and releasing human chorionic gonadotropin (hCG) into your blood and pee. HCG can be found in a person’s blood around 11 days after conception. It takes slightly longer for hCG to show up on at-home pregnancy tests (that measure hCG in pee).

What are my chances of conceiving?

Just because an egg and sperm are near each other doesn't mean conception will happen. In general, conception only happens 25% to 30% of the time. This percentage decreases once you reach age 35.

How does conception work with IVF?

Conception still works the same way — sperm must fertilize an egg. However, with in vitro fertilization (IVF), 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.

When does conception happen?

Conception occurs between 12 and 24 hours after ovulation. It’s sometimes hard to pinpoint ovulation, so using ovulation predictor kits or tracking your menstrual cycle on a calendar may be helpful. The two biggest factors in conception are:

The timing of sexual intercourse with ovulation.
Egg and sperm health.

When should I have sex to conceive?

Conception can happen after unprotected sex as early as five days before ovulation. This is because some sperm can live that long inside female reproductive organs.

If you’re trying to conceive, the best times to have sex are:

In the three days before ovulation: In this scenario, sperm will be “waiting” for the egg to come down the fallopian tube.
At ovulation or within 24 hours of ovulating: Your egg lives for only 24 hours, so if you have unprotected sex during this time, your egg may end up “waiting” for sperm to reach it, or they may run into each other in your fallopian tubes.

Where does conception happen?

Conception typically happens in your fallopian tubes. This is where an egg goes after it leaves your ovary and where sperm wait for an egg. In some cases, fertilization can happen in your uterus once your egg has left your fallopian tubes.

What things prevent conception from happening?

Certain health conditions may affect your ability to conceive. Just because the sperm and egg meet doesn't mean fertilization will occur. Some of the most common factors are:

Anovulation (you’re not ovulating).
Low sperm count or issues with sperm motility (how sperm move).
A blockage in the testicles, ovaries or fallopian tubes.
Decreasing amount of quality eggs and quality sperm (usually related to aging).

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 don’t have any pregnancy symptoms for weeks after a positive test.

Common signs of pregnancy are:

A missed period.
Frequent urination.
Feeling tired.
Nausea.
Sore or swollen breasts.
Spotting (light vaginal bleeding).
Headaches.
Mood swings.

Take a home pregnancy test if you have any of the above symptoms and think there’s a chance you’re pregnant. Your healthcare provider can order a blood test to confirm pregnancy.

Are conception and fertilization the same?

Conception and fertilization are two different parts (or steps) of the same process. Conception is the first step, where an egg and sperm join. Fertilization is another step, where the joined sperm and egg plant like a seed into your uterine lining.

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 (hCG), 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. It’s 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 you’re struggling with conceiving. They can explain the process and identify any issues preventing conception and pregnancy.

Conception: How It Works | Patient Education

To become pregnant, the following steps must occur:

Sperm transport — The sperm must be deposited and transported to the site of fertilization.
Egg transport — Ovulation must occur and the egg must be "picked up" by the tube.
Fertilization and embryo development — Union between the sperm and egg must result.
Implantation — The embryo must implant and begin to grow in the uterus.

These steps are described below.

Sperm Transport

The transport of sperm depends on several factors:

The sperm must be capable of propelling themselves through the environment of the female vagina and cervix.
This environment, which is under cyclic hormonal control, must be favorable to admit the sperm without destroying them.
The sperm must possess the capability of converting to a form that can penetrate the cell membrane of the egg (capacitation).

Following ejaculation, the semen forms a gel that protects it from the acidic environment of the vagina. The gel is liquefied within 20 to 30 minutes by enzymes from the prostate gland. This liquefaction is important for freeing the sperm so transportation may occur. The seminal plasma is left in the vagina.

The protected sperm with the greatest motility travel through the layers of cervical mucus that guard the entrance to the uterus. During ovulation, this barrier becomes thinner and changes its acidity, creating a friendlier environment for the sperm. The cervical mucus acts as a reservoir for extended sperm survival.

Once the sperm have entered the uterus, contractions propel the sperm upward into the fallopian tubes. The first sperm enter the tubes minutes after ejaculation. The first sperm, however, are likely not the fertilizing sperm. Motile sperm can survive in the female reproductive tract for up to five days.

Egg Transport

Egg transport begins at ovulation and ends once the egg reaches the uterus. Following ovulation, the fimbriated, or finger-like, end of the fallopian tube sweeps over the ovary. Adhesive sites on the cilia, which are located on the surface of the fimbriae, are responsible for egg pickup and movement into the tube. The cilia within the tube, and muscular contractions resulting from the movement of the egg, create a forward motion. Transport through the tube takes about 30 hours.

Conditions such as pelvic infections and endometriosis can permanently impair the function of the fallopian tubes, due to scarring or damage to the fimbriae.

Fertilization and Embryo Development

Following ovulation, the egg is capable of fertilization for only 12 to 24 hours. Contact between the egg and sperm is random.

Once the egg arrives at a specific portion of the tube, called the ampullar-isthmic junction, it rests for another 30 hours. Fertilization — sperm union with the egg — occurs in this portion of the tube. The fertilized egg then begins a rapid descent to the uterus. The period of rest in the tube appears to be necessary for full development of the fertilized egg and for the uterus to prepare to receive the egg.

Defects in the fallopian tube may impair transport and increase the risk of a tubal pregnancy, also called ectopic pregnancy.

A membrane surrounding the egg, called the zona pellucida, has two major functions in fertilization. First, the zona pellucida contains sperm receptors that are specific for human sperm. Second, once penetrated by the sperm, the membrane becomes impermeable to penetration by other sperm.

Following penetration, a series of events set the stage for the first cell division. The single-cell embryo is called a zygote. Over the course of the next seven days, the human embryo undergoes multiple cell divisions in a process called mitosis. At the end of this transition period, the embryo becomes a mass of very organized cells, called a blastocyst. It's now believed that as women get older, this process of early embryo development is increasingly impaired due to diminishing egg quality.

Implantation

Once the embryo reaches the blastocyst stage, approximately five to six days after fertilization, it hatches out of its zona pellucida and begins the process of implantation in the uterus.

In nature, 50 percent of all fertilized eggs are lost before a woman's missed menses. In the in vitro fertilization (IVF) process as well, an embryo may begin to develop but not make it to the blastocyst stage — the first stage at which those cells destined to become the fetus separate from those that will become the placenta. The blastocyst may implant but not grow, or the blastocyst may grow but stop developing before the two week time at which a pregnancy can be detected. The receptivity of the uterus and the health of the embryo are important for the implantation process.

1-4 weeks of pregnancy

From a tiny fetus to a small person, a child's body develops in just 9 months. What changes are happening to the expectant mother and what changes are observed inside her during this difficult and joyful period of life?

Each new life begins with the union of the egg and sperm. Conception is the process by which a sperm enters an egg and fertilizes it.

It should be noted that the embryonic and obstetric terms are different. The thing is that among specialists it is customary to consider the period from the first day of the last menstruation, that is, the obstetric period includes the period of preparation for pregnancy. So it turns out that the embryo has just appeared, and the gestation period is already two weeks. It is the obstetric period that is indicated in all the documents of a woman and is the only reporting period for specialists.

Until the moment of the meeting, the spermatozoon and the ovum lived for a certain time, being in the stage of development and maturation. The development of the future fetus significantly depends on the quality of these processes.

First week

Growth and maturation of the egg starts from the first day of the cycle. A mature egg contains 23 chromosomes as the genetic material for the future embryo, and also contains all the nutrients necessary to start its development. It contains reserves of carbohydrates, proteins and fats, designed to support the embryo during the first days after its occurrence.

A certain number of eggs are laid in each ovary of a girl before she is born. During the childbearing period, they only grow and develop, the process of their formation does not occur. By the time a girl is born, the number of cells from which eggs can develop in the future reaches a million, but this number decreases significantly over the course of life. So, by the time of puberty, there are several hundred thousand of them, and by maturity - about 500.

The ovary each month gives the opportunity to develop most often one egg, the maturation of which occurs inside a vesicle with a liquid called a follicle. From the first day of the cycle, the uterine mucosa begins to prepare for a possible pregnancy. For implantation, i.e., the introduction of the resulting embryo into the wall of the uterus, an optimal environment is created. To do this, due to the influence of hormones, the endometrium thickens, it becomes covered with a network of vessels and accumulates the nutrients necessary for the future embryo.

Male reproductive cells are formed in the gonads - in the testicles or testes. The maturation of spermatozoa occurs in the epididymis, into which they move after formation. The liquid structure of semen is formed due to the secretion of the seminal vesicles and the prostate gland. A liquid medium is necessary for storing mature spermatozoa and creating favorable conditions for their life.

The number of spermatozoa is quite large: tens of millions in one milliliter. Despite such a significant number, only one of them will be able to fertilize the egg. In spermatozoa, there is exclusively genetic material - 23 chromosomes, which are necessary for the appearance of the embryo.

Spermatozoa are characterized by high motility. Once in the female genital tract, they begin their movement towards the egg. Only half an hour or an hour passes from the moment of ejaculation, when sperm enter the uterine cavity. It takes one and a half to two hours for spermatozoa to penetrate into the widest part, which is called the ampulla. Most spermatozoa die on the way to the egg, meeting the folds of the endometrium, getting into the vaginal environment, cervical mucus.

Second week

In the middle of the cycle, the egg fully matures and leaves the ovary. It enters the abdominal cavity. This process is called ovulation. With a regular cycle of 30 days, ovulation occurs on the fifteenth. The egg is unable to move on its own. When she leaves the follicle, the fimbriae of the fallopian tube ensure her penetration inside. The fallopian tubes are characterized by longitudinal folding, they are filled with mucus. The muscular movements of the tubes have a wave-like character, which, with a significant number of cilia, creates optimal conditions for transporting the egg.

Through the tubes, the egg enters their widest part, which is called the ampulla. This is where fertilization takes place. If there is no meeting with the sperm, the egg dies, and the female body receives the appropriate signal to start a new cycle. There is a rejection of the mucous membrane, which was created by the uterus. The manifestation of such rejection is bloody discharge, which is called menstruation.

The waiting period for fertilization by the egg is short. On average, it takes no more than a day. Fertilization is likely on the day of ovulation and maximum on the next. Sperm have a longer lifespan, averaging three to five days, in some cases seven. Accordingly, if a spermatozoon enters the female genital tract before ovulation, there is a possibility that it will be able to wait for the appearance of an egg.

When the egg is in a state of waiting for fertilization, certain substances are released that are designed to detect it. If spermatozoa find an egg, they begin to secrete special enzymes that can loosen its shell. As soon as one of the spermatozoa penetrates the egg, the others can no longer do this due to the restoration of the density of its shell. Thus, one egg can only be fertilized by one sperm.

After fertilization, the chromosome sets of the parents merge - 23 chromosomes from each. As a result, one cell is formed from two different cells, which is called a zygote. The sex of the unborn child depends on which of the chromosomes, X or Y, was in the sperm. Eggs contain only X chromosomes. When XX is combined, girls are born. If the spermatozoon contains a Y chromosome, that is, with a combination of XY, boys are born. As soon as a zygote is formed in the body, a mechanism is launched in it aimed at maintaining pregnancy. There are changes in the hormonal background, biochemical reactions, immune mechanisms, and the receipt of nerve signals. The female body creates all the necessary conditions for the safe development of the fetus.

Third week

As soon as a day has passed after the formation of the embryo, he will need to make his first journey. The movements of the cilia and the contraction of the muscles of the tube direct it into the uterine cavity. During this process, inside the egg, fragmentation into identical cells occurs.

After four days, the appearance of the egg changes: it loses its round shape and becomes vine-shaped. This stage is called morula, embryogenesis begins - an important stage in the development of the embryo, during which the formation of the rudiments of organs and tissues occurs. Cleavage of cells continues for several days, on the fifth day their complexes are formed, which have different functions. The central cluster forms directly the embryo, the outer one, called the trophoblast, is designed to melt the endometrium - the inner layer of the uterus.

It takes 5-7 days for the embryo to reach the uterus. When implantation occurs in its mucous membrane, the number of cells reaches one hundred. The term implantation refers to the process of implantation of the embryo into the endometrial layer.

After fertilization on the seventh or eighth day, implantation takes place. The first critical period of pregnancy is this stage, since the embryo will have to demonstrate its viability for the first time.

During implantation, the outer cells of the embryo actively divide, and the process itself takes about forty hours. The number of cells outside the embryo increases dramatically, they stretch, they penetrate into the uterine mucosa, and the thinnest blood vessels are formed inside, which are necessary for the supply of nutrients to the embryo. Time will pass, and these vessels will be transformed first into the chorion, and subsequently into the placenta, which will be able to supply the fetus with everything necessary until the baby is born.

The embryo at this stage of life is called a blastocyst. It contacts with the endometrium, melts the cells of the endometrium with its activity, creates a path for itself to the deeper layers. The blood vessels of the embryo intertwine with the mother's body, which allows it to immediately begin to extract useful and necessary substances for development. This is vital, because by this time the stock that the mature egg carried in itself is exhausted.

Next, the production of the trophoblast cells, i.e., the outer cells of human chorionic gonadotropin, the hCG hormone, begins. The distribution of this hormone throughout the body notifies it of the onset of pregnancy, which causes the launch of active hormonal changes and the beginning of corresponding changes in the body.

After fertilization and before the start of hCG, it usually takes eight or nine days. Therefore, already from the tenth day after fertilization, it becomes possible to determine this hormone in the mother's blood. Such an analysis is the most reliable confirmation of the onset of pregnancy. The tests that are offered today to determine pregnancy are based on the detection of this hormone in the urine of a woman. After the first day of delayed menstruation with its regular cycle, it is already possible to determine pregnancy using a test on your own.

What happens to a woman in the third week of pregnancy

If a woman is planning a pregnancy, 21-24 days, subject to a regular cycle, should become important for her. This is a period of possible implantation, when you should pay special attention to your own lifestyle. During this period, thermal effects and excessive physical exertion are undesirable, and the influence of various kinds of radiation should also be prevented.

The woman does not feel anything at this stage, because implantation has no external signs. If you adjust your lifestyle in accordance with the simple rules listed above, you will be able to create optimal conditions for successful implantation.

Fourth week

In the fourth obstetric week or the second week of the fetus's life, its body consists of two layers. Endoblast - cells of the inner layer - will become the beginning of the digestive and respiratory systems, ectoblast - cells of the outer layer - will start the development of the nervous system and skin.

The size of the embryo at this stage is 1.5 mm. The flat arrangement of the cells determined the name of the embryo of this age - the disc.

The fourth week is characterized by intensive development of extra-embryonic organs. Such organs should surround the embryo and create the most favorable conditions for its development. The future fetal membranes at this stage are called the amniotic sac, the chorion also develops, which will later become the placenta, and the yolk sac, which is a warehouse of nutrients needed by the embryo.

What happens to a woman in the fourth week of pregnancy

If a woman experiences changes in the fourth week, they are very minor. So far, hormones have not reached the level to have a significant impact on her health. Possible drowsiness, mood swings, increased sensitivity of the mammary glands.

The main helpers of the expectant mother in the fourth week, as well as throughout pregnancy, are fresh air, properly selected nutrition and good mood.

〚 How long does it take to get pregnant after sex? 〛Babystart official distributor

January 26, 2020

How early can you check?

Can you improve your chances?

Pregnancy may seem like a rather mystical process. Once you study the question, it will become clearer. However, you may wonder how long it takes to conceive a child after sex.

Short answer: egg and sperm can meet for a few minutes to 12 hours after ejaculation. But to see that second line on a pregnancy test, you still need to overcome some hurdles.

Here's more on how reproduction works (in super simple terms) and how to time it and possibly improve your chances of getting pregnant.

Fertilization occurs when the egg and sperm meet in the fallopian tube. For this to happen, the woman must be in her fertile window. This means that she is approaching or has reached ovulation, the point in each menstrual cycle when an egg is released from the ovary.

The egg can only be fertilized between 12 and 24 hours from its release. After that, it begins to break down, hormones shift, and eventually, the period begins the next cycle.

Although it seems that the chances of catching an Egg are rather small, consider the numbers. Ejaculate is estimated to contain up to 280 million trusted source sperm. And under ideal conditions, sperm cells actually live for several days in the reproductive tract.

Any unprotected sex within 5 days of ovulation can cause sperm to wait and be ready for fertilization. In other words, you can get pregnant after intercourse almost a week before ovulation if healthy sperm is already dangling at its final destination.

On the other hand, conception can occur very soon after sex. Experts say that sperm can travel through the uterus and fallopian tubes to reach the egg as early as 30 minutes after ejaculation.

When does implantation take place?

After fertilization, the new zygote moves through the fallopian tube and undergoes tremendous changes. It develops into a morula and then a blastocyst. Once it reaches the blastocyst stage, it is ready to implant in the uterine lining and continue to grow into the fetus.

Implantation is necessary to achieve pregnancy. Without this, the blastocyst will break and be removed with the rest of the uterine lining during menstruation.

In terms of timing, implantation usually occurs between 6 and 10 days after fertilization. The symptoms you may experience are mild and include things like spasms and light patches. However, some women may not notice any symptoms at all.

When do symptoms start?

As soon as the implanted embryo begins to produce hormones (which is immediate), pregnancy symptoms may begin.

The earliest symptoms include:

Missed period. If you have a late period, you may be pregnant. Hormones produced by the growing fetus signal to the brain that the lining of the uterus is preserved.
Changes in your breasts. Your breasts may feel tender or swollen to the touch due to hormonal changes.
Morning sickness. Although this symptom usually starts about a month after implantation, it may start earlier in some women. You may experience nausea with or without vomiting.
Frequent trips to the toilet. Your kidneys overgrow during pregnancy because they are tasked with processing extra fluids due to increased blood volume. This means increased urination.
Fatigue. You may feel tired in early pregnancy. Hormones, again, play here. In particular, the hormone progesterone can make you especially malnourished.

If you are experiencing these symptoms or otherwise think you are pregnant, a home pregnancy test is recommended.

When can you get a positive pregnancy test result?

Home pregnancy tests measure the amount of human chorionic gonadotropin (hCG) in your urine. It is produced after egg implantation, but not at detectable levels until 6-14 days after fertilization. Your most reliable results will start on the day of your missed period, as all cycles are unique.

You can buy the test in supermarkets, pharmacies or online. Follow all instructions and consult your doctor if you test positive or if you test negative but your period does not start.