Nesting: what is it, does it have symptoms and when does it occur?

Nesting is one of the early signs of pregnancy. It means that the fertilized egg was implanted in the uterine wall. When it happens, it can cause some symptoms, like a little bleeding.

Often, this nidation blood is not recognized by women, as it is mistaken for an escape from menstruation.

From the nesting, the whole development of a pregnancy begins, such as the formation of the placenta and the production of hormones such as human chorionic gonadotropin, HCG. It is with the presence of this hormone that pregnancy is confirmed.


What is nesting?

Nesting is a natural state, characterized by the implantation of the embryo in the woman’s uterus . It occurs one week after the ovulatory period, being the initial stage of pregnancy.

The female reproductive system is composed of the ovaries (which generate the eggs), the uterine tubes (which transport the eggs that have crossed the surface of the ovary to the uterine cavity), the uterus (which receives the fertilized egg, providing the necessary conditions development), vagina and vulva.

The uterus is an empty organ with thick muscle walls. In addition to housing the embryo, the uterus has a passage that allows the sperm to reach the fallopian tube.

The embryo, in turn, corresponds to the development phase that lasts until the 8th week of gestation.

The implantation can cause a small bleeding, which is often confused with menstruation, known as Hartman’s sign .

Although all future mothers go through the nesting, not all of them show symptoms. Only 20% of them have bleeding when the egg is fixed.

Nesting symptoms are mild. In general, only a few women are able to recognize the evidence. Pregnancy tests and blood tests can be done to have a confirmation.

When does fertilization occur?

Before starting the implantation, the process of fertilization or fertilization occurs, as it is also called. Fertilization is part of the sexual reproduction process, in which two types of sexual reproductive cells or gametes (egg and sperm) fuse.

Sex cells contain genetic information that has particularities that will be passed on to the next generation. Each of them has half the genetic material of the mother (egg) and half of the father (sperm).

When the two fuse, the zygote, or egg cell, as it is also called, is formed. This process is called heredity.

It is through sexual intercourse that sperm are sent inside the woman’s body to reach the egg.

The male gamete is attracted to chemicals released by the egg and try to reach it. Substances in the semen also favor its displacement, as they encourage contractions in the muscles of the uterus.

This movement, combined with that of the flagella, (a structure linked to the plasma membrane of cells with locomotor function) allows the transport of male gametes to the uterine tube.

The vast majority of sperm die on the way, as the vaginal area is acidic, in addition to having defense cells.

When the sperm reaches the vitelline membrane – the outermost layer of the egg – the membrane of the acrosome (vesicle with several digestive enzymes, found in the head of the sperm) joins the membrane of the egg, releasing the enzymes.

The enzymes in the acrosome dismantle the vitelline membrane, which allows sperm to pass through. The fusion between the membrane of the male gamete and the membrane of the egg allows the nucleus of the sperm to reach the egg.

Once this is done, the egg membrane has chemical and electrical changes, becoming a fertilization membrane, preventing other sperm from entering.

With its introduction, fertilization begins when the structures of the sperm unite with that of the egg, giving rise to the zygote. This process takes place 24 hours after the sperm enters the uterus.

The zygote passes through several cell divisions, generating the embryo, which will develop, forming a new individual.

How does nesting happen?

The sperm is active in the woman’s body for up to 5 days. When the woman ovulates, the egg generated resists for around 12 to 24 hours, which is the time the sperm has to carry out fertilization. When constituted, the zygote travels for a period of up to 5 days to reach the uterus.

The embryo implantation occurs in 3 stages:

  • In the first stage, known as implantation of the egg, the new embryo is called a blastocyst and joins the uterine walls. At this stage, the embryo is around 5 to 6 days old;
  • In the second stage, the egg passes through the uterine wall to be protected, adhering to the endometrium (mucosa that lines the inside of the uterus);
  • In the third stage, fixation in the uterus is complete. The egg is located in the endometrial cavity.

The implantation of the egg marks the beginning of pregnancy. When the embryo adheres to the wall of the uterus, small veins and arteries in the uterine membrane can rupture, resulting in blood loss.

When does nesting take place?

Nesting occurs when the fertilized egg is implanted in the uterine wall. On average, it takes 5 days between the sexual act and the nesting. However, not all women have obvious symptoms when it occurs, such as nesting bleeding.

In fact, it is estimated that only 20% of pregnant women experience this sign, and in most cases, it is very punctual. However, sometimes it can last for up to 3 days.

When do symptoms occur?

For the baby to develop, it is necessary that the uterus adapts to enable its development. It is as if the uterus needed to make a bed where the embryo will be lodged. To do this, the endometrium “thickens” and it is ready with all the nutrients necessary for the implantation and nutrition of the embryo.

When the embryo is fixed in the “walk”, it can trigger the flaking of the endometrium and if there is access, the blood can be expelled through the vagina. Normally, nesting bleeding occurs without the presence of flow and for a short period of time.

The symptoms of nesting appear between 7 and 15 days after the fertile period (14 days before the start of menstruation, in a cycle of 28 days), varying in intensity for each woman. However, indications of nesting can occur at the end of the cycle, close to the date of the onset of menstruation.

In situations of long ovulation, symptoms can appear up to 15 days after ovulation.

During pregnancy, a woman develops the Human Karyonic Ganadatrophin (HCG) hormone – which aims to prevent the corpus luteum from being destroyed. The corpus luteum produces and releases progesterone , which prepares a woman’s body for pregnancy.

Pregnancy tests measure the amount of HCG for an assertive result. It is also through him that the approximate time of gestation is determined.

Symptoms of nesting: how to know if it occurred?

The evidence of nesting includes:

  • Failure of the menstrual period;
  • Bleeding.

1 in 3 women have symptoms, which are often not noticed, as they vary in intensity according to each person. Other symptoms that may occur at the beginning of pregnancy are:

  • Motion sickness;
  • Vomiting;
  • Sleep and tiredness;
  • Pressure in the lower part of the belly;
  • Melasma (dark spots on the skin).

In addition, hormonal changes are primarily responsible for changes in the woman’s physical and emotional state. Other signs can help to identify a pregnancy:

Breast tenderness

As hormones change, the breasts may become swollen or tender.

Mood swings

Mood swings, becoming more sentimental than normal, are quite common signs.


The swelling can appear at the beginning of the menstrual period, but it can also be an indication of a possible pregnancy.

Food repulsion

Being repulsed by certain flavors or odors, particularly by food.

Nasal congestion

Hormones can cause swelling in the mucous membranes in the nose, making them liquid or congested. Nasal bleeds can also occur.


Hormonal variations can affect a woman’s digestive system.

Basal temperature rise

Basal body temperature (TCB) is higher during implantation and can be measured immediately after waking up in the morning. The level of TCB is higher when ovulation occurs, due to the increase in the hormone progesterone and remains elevated during implantation.

Urinating frequently

The urge to urinate intensifies one week after implantation. Among the bodily changes to shelter the baby, there is an increase in blood supply in the pelvic region, which causes pressure on the bladder. This pressure is the reason for the strong desire to urinate.

Heat waves

Uncommon in implantation processes, heat waves usually last 15 minutes at the time of implantation. This is because the hormones fluctuate quickly, culminating in hot flashes.


Counting from the moment of fertilization, the egg cell travels its way to the uterus at the same time that cell division begins.

The contraction movement of the tubes when carrying the eggs to the uterus, can cause discomfort and the sensation of colic.

What are the characteristics of nesting bleeding?

In general, there are some characteristics of nesting bleeding that differ from menstrual bleeding. It tends to be more watery and fluid, much less intense. For this reason, it tends to have a more pink color.

It also occurs in less quantity, without a small flow and, in most cases, punctual – although some women may experience bleeding for up to 3 days. Mild cramps may occur with the nest, but this is not a rule.

Does nesting bleed smell?

No. Bleeding from the nest has an odor similar to the natural secretion of the healthy vagina. Thus, if bleeding or discharge is accompanied by a noticeable change in odor, it is worth seeking medical advice.

Causes of bleeding during pregnancy

Even during pregnancy, the woman may be affected by bleeding caused by other factors, in addition to nesting.

Some of them are:

Menstrual failure

The completion of the nesting process corresponds to the date on which the woman should start menstruating again, taking into account a 28-day cycle. Therefore, menstrual failure can be pointed out as one of the first symptoms of nesting.


Bleeding is one of the most common signs of nesting. It appears lightly, for a period of up to 3 days. However, it is only with the appearance of HCG in the body that it can be guaranteed that the bleeding was caused by the nesting.


Recurring in early pregnancy, bleeding due to sexual intercourse can also occur at any gestational period. Hormonal changes may be related to the problem. In general, bleeding stops on its own.

Ectopic pregnancy

Characterized by the implantation of the embryo outside the uterus, ectopic pregnancy can trigger bleeding accompanied by pain and cramps. This condition is very dangerous. The consultation with a doctor should be done as soon as possible.


Around 15% of women suffer spontaneous abortion in the first months. The signs are usually bleeding and colic.

Other causes of bleeding

It is worth mentioning that not all light and lighter colored bleeding that appears within the menstrual cycle originates from nesting. Other possible causes involve:


Most of the time, bleeding is the result of the normal ovulation process, which may appear 14 days before menstruation, but which is not usually repeated.


Deprivation or reaction of the body to certain medications, such as contraceptives or the morning-after pill can cause bleeding.

How long does the nesting take?

Normally, symptoms of nesting last for 1 week, but in rare cases, it can last for 2 weeks. As it is a normal process, women need not worry, as the symptoms disappear on their own. It is worth mentioning that the nesting bleeding should not exceed the period of 3 days, without the occurrence of flow.

Low levels of the hormone progesterone can pose risks for pregnancy. Because of this, consultation with the gynecologist is necessary.

What does the nesting bleed look like?

Its color may be brownish red, pink or watery in appearance. Bleeding can also present as a brown sludge or discharge. It is worth mentioning that it should not have volume or flow.

What factors can harm nesting?

Some factors can impair the nesting process. Are they:

Changes in the structure of the endometrium

Changes in the structures of the endometrium can make pregnancy difficult.

Non-trilaminate endometrium

The endometrium needs to be of adequate thickness so that the embryo can fix. The trilaminar endometrium is defined by 3 different layers.

Thin endometrium

The endometrium needs to be 7 to 14 millimeters to provide a pregnancy.

Thin endometrium or Asherman’s Syndrome, is when the thickness of the endometrium is below 6 millimeters in the implantation phase.

The problem makes pregnancy difficult, as the endometrium does not have the depth necessary for implantation of the embryo, so the abortion rate in these cases is very high.

It becomes thin due to monthly flaking when implantation does not occur, which results in uterine walls with intrauterine synechiae (connections of the scar tissue with opposite uterine walls) and scars. Such abnormalities can cause female infertility.


Endometriosis is a disorder in which the endometrium grows outside the uterus, and can affect regions such as tubes, ovaries and intestines.

The cause of the disease is unknown, but if close family members, such as mother and sister have endometriosis, the chances increase.

Non-uterine problems

Beaked and septate uterus can interfere with nesting.

Bicornuate uterus

Bicornuate uterus or uterus with two “horns”, as it is also called, refers to a deformation in the aspect of the organ. Its cause is related to a membrane that causes uterine separation, which can be partial (in a Y shape) or absolute, dividing the uterus into two parts.

As for pregnancy, there are chances of spontaneous abortions and premature births.

Septate uterus

Like the bicornuate uterus, the septate uterus presents partial or total division. However, this bifurcation is caused by a wall.

At about 9 weeks of gestation, the girl has her uterus formed. For this, the Muller ducts (channels that form the uterine tubes, uterus and most of the upper region of the vagina) must come together.

During this stage, two ducts must merge and form a single cavity. For no apparent reason, in some girls the process is incomplete, which results in a thin membrane called the septum. This membrane divides the uterus.

Differences between breeding bleeding and menstruation

Nesting bleeding may appear brownish or pink. In general, it has small blood fragments. Its quantity is low, just soiling the panties or shown on the toilet paper. Cramping is continuous, but in a moderate way.

Menstruation is differentiated by the volume of blood, which is greater, and by its color, an intense red. In addition, menstrual flow usually lasts longer, with cramps being more intense.

When to seek medical help?

In cases of suspected pregnancy due to delayed menstruation or the presence of symptoms of nesting, the woman may see a doctor in order to clear up the doubt.

However, some signs indicate that there is something wrong, which needs to be evaluated and addressed. Some are:

  • Abundant bleeding, lasting more than 3 days, with intense color;
  • Severe abdominal pain;
  • Fever.

Nidation and abortion

Abortion is a topic that raises several questions and opinions, whether contrary or favorable. However, by law, life is supported after nesting.

Therefore, as long as there is no implantation of the embryo, it is not possible to guarantee protection through criminal law.

The morning-after pill, for example, is a compound with high doses of levonorgestrel. It is a device used as an emergency to prevent pregnancy. Even considered abortive, for not allowing the implantation of the egg, it is not seen as a crime.

Common questions

Does nesting smell?

No . Bleeding caused by nesting does not have a strong or specific odor. If the discharge has a more pronounced smell, it may be an indication of infection.

What happens to the cervix in the nest?

The cervix is ​​a lower part of the uterus, where the orifice of the organ is located, located in the concave of the vagina.

Its shape is cylindrical, with an opening in the central region, called the cervical canal, through which the menstrual flow and sperm pass. It also separates the internal and external organs and allows the baby to pass through during delivery.

In general, during nesting, its state remains the same: closed, tall and with a thicker thickness. However, their appearance may vary depending on the person.

Does implantation bleeding pose risks?

No , nesting bleeding has no risks. However, it becomes alarming if the bleeding continues for more than 3 days and if the color is a bright red, similar to that of menstruation.

Having intercourse in the fertile period and bleeding, can it be nesting?

No , because it is still too recent to have the implantation of the zygote.

After nesting symptoms, how long should I wait to take the pregnancy test?

On average, 1 in 3 fertilized eggs progress to pregnancy. In theory, the pregnancy test should be done instantly or 24 hours after the appearance of the nesting symptoms. However, the body’s reaction is different for each woman.

In general, the positive result appears at the end of the 5th week without menstruating.

HCG levels increase until the 20th day after ovulation and gradually decrease from the 10th week until the end of pregnancy.

For the result to be positive, HCG levels must be above 5 IU / L.

Does twinning have a distinction?

The symptoms are the same as for a single pregnancy. It is also not possible to distinguish how many babies are in the womb just by nesting.

How to increase the possibility of nesting?

The best way to get pregnant is to know the dates of the cycle and the fertile period. Having sex during the fertile period is one of the most efficient ways to get a positive test.

Nesting is a natural process, considered the early stage of pregnancy. Implantation of the embryo in the uterus can trigger bleeding and other symptoms, but not all women have them. Stay tuned, as the next future mommy could be you!

Share this information with family and friends!