First trimester of pregnancy: changes in a woman’s body and fetal development by week

Every woman's pregnancy experience is unique. Of course, not all women have the same symptoms or even the same signs from one pregnancy to the next.

And because early signs of pregnancy often mimic symptoms that may occur before and during menstruation, a woman may not realize she is pregnant.

In this article, we will look at various symptoms and signs that may indicate a possible early pregnancy.

When might the first signs of pregnancy appear?

This may seem strange, but in obstetrics the gestational age is counted from the last day of menstruation.

The main signs of pregnancy starting from the 1st obstetric week:

Let's take a closer look at the 10 most common early pregnancy symptoms. It is important to know that these symptoms can not only be caused by pregnancy, but can also be associated with various health conditions. Therefore, the presence of these symptoms does not necessarily indicate that you are pregnant.

Delayed menstruation (missed menstrual cycle)

With a normal menstrual cycle with ovulation on days 14-15, a delay occurs 2 weeks after conception, since after the end of implantation of blastocytes, human chorionic gonadotropin (hCG) is produced, which helps the body maintain pregnancy, and the ovaries stop releasing mature eggs. But it is worth noting that a missed cycle is not always caused by pregnancy; it is better to confirm this with a pregnancy test, especially if you have an irregular cycle for some reason. In addition, you need to know that some women may experience bleeding during pregnancy. If you are pregnant, ask your doctor about bleeding as a natural process and as a sign of an emergency.

Most home tests can detect hCG as early as 8 days after a missed cycle.

Clue

• Take a pregnancy test.
• If the result is positive, call your doctor to schedule your first appointment.
• If you are taking any medications, ask your doctor if they pose any risk to you and your unborn baby.

In addition to pregnancy, there are various reasons why a delay may occur, such as sudden weight gain or loss. Fatigue, hormonal problems, stress - all this can contribute to cycle disruption. Some women experience a delay when they stop taking birth control.

Conception

The sacrament of the fusion of two sex cells - the egg and the sperm, as a rule, occurs 14-13 days before menstruation. But sometimes a woman’s ovulation day in her menstrual cycle shifts by several days. The reason for this may be stress, illness, sudden climate change...

To accurately determine the favorable day of conception, auxiliary methods come to the rescue. An ovulation test is often used. This is an easy, simple and affordable way. To conduct the study, saliva or urine is used (read the instructions for each test) and the test itself. Currently, there are many types of tests, but the meaning is the same - determining the level of luteinizing hormone. This hormone is produced by the pituitary gland and LH peaks one day before ovulation. The test is considered positive when the test line is the same or brighter than the control line. If you receive a positive result, this and the next few days will be the most favorable for conceiving your baby.

Another popular and informative method is folliculometry. This is multiple ultrasounds performed in one menstrual cycle. During the study, the dominant follicle is determined, its maturation is monitored and the fact of ovulation is established. The doctor calculates the dates individually, based on the duration of the menstrual cycle. Subtract 14 from the days of the menstrual cycle to get the day of ovulation in the menstrual cycle.

For example: the menstrual cycle is 30 days - 14 = 16. Ovulation occurs on the 16th day of the menstrual cycle. The first ultrasound is performed 6 days before ovulation. The calculation is carried out using the formula 16-6=10. In this example, it is the 10th day of the menstrual cycle. At the first ultrasound, the doctor will determine the next visit. More often it is 3 studies per cycle.

We must not forget about the old proven method - basal temperature. Temperature is measured in the rectum from the first day of the menstrual cycle, in the morning, at the same time, without getting out of bed, with the same thermometer. The results are recorded on the coordinate axis and the result is evaluated. Before ovulation, the temperature decreases, during ovulation and in the second phase of the cycle it increases by 04.0-0.6 degrees. The day with a decrease in temperature and the next day or two will be considered favorable for conception.

The long-awaited day of ovulation has arrived. Exciting anticipation begins.

Fatigue

Feeling tired can develop at any stage of pregnancy and is quite normal, but it is very common in early pregnancy. Fatigue and drowsiness can cause an increase in the level of the hormone progesterone. Of course, you can't rule out other factors that contribute to fatigue, such as low blood sugar, increased blood production or low blood pressure.

Clue

• Try to get enough sleep and maintain a rest routine.
• Ventilate the room before going to bed and spend time in fresh air often - this can help.
• Eat foods rich in protein and iron.

Breast changes: tingling, pain, growth

Breast changes may appear between the 4th and 6th weeks. Due to changes in the level of female hormones, the breasts may become swollen or tingling. Women may feel that their breasts are heavier or fuller, and may also experience increased sensitivity. This usually goes away after a few weeks as the body gets used to the hormones.

Nipple and breast changes may also occur at 11 weeks. Hormones promote breast growth. The areola, the area around the nipple, may change to a darker color and become larger.

Keep in mind that it will take a few weeks for your body to get used to the hormonal changes.

Clue

• You can reduce sensitivity in your breasts by purchasing a comfortable maternity bra. A cotton bralette is often the most comfortable
• It is better to choose one bra with different levels of clasps, with which you can adjust the size in the coming months
• Invest in breast pads, such as bamboo pads, that are inserted into your bra to reduce friction and nipple pain.

It is important!

• Protein is needed for normal sperm viability and motility, so it is important for a man to monitor the amount in his diet. The female body must also receive enough proteins: this is a building material for the body.
• It is important to control the amount of fat. Both a lack and excess of fats in the diet can affect hormonal levels. It is worth observing the golden mean.
• It is better for both men and women to avoid foods containing large amounts of chemical additives, as well as alcohol.

Physical exercise.

Physical inactivity harms all systems of the body, including reproductive. Moderate physical activity is indicated to improve metabolism, which in turn increases the likelihood of conception. Of course, excessive fanaticism, as in the case of nutrition, is inappropriate: excessive overload will only harm the body and reduce the likelihood of getting pregnant. It is necessary to maintain a level of physical activity that does not cause serious stress to the body. This will allow:

• keep the body in good shape;
• normalize metabolism;
• strengthen muscles, which is especially important for successful pregnancy;
• improve sleep;
• increase libido.

The effect of physical activity on emotional well-being is also important. Stress reduces your chance of getting pregnant, and moderate activity is a good way to relieve it. It is recommended for both parents to reconsider their lifestyle: both the female and male reproductive systems will benefit from healthy exercise. If the couple has already practiced sports or fitness, they can continue, but avoiding overload.

Cramps and discharge

The body of a pregnant woman at 1-4 weeks begins to change at the cellular level. A blastocyst (a group of cells on days 5-6 of embryo development), created from a fertilized egg, will subsequently form into the body parts and organs of the child.

After about 10 to 14 days (week 4), the blastocyst will implant in the endometrium, the lining of the uterus, which can cause implantation bleeding, which some women mistake for a light menstrual cycle, which usually lasts 3 to 12 days after the egg is fertilized.
4 common signs of implantation bleeding:
Pain. The pain may be mild, moderate, or severe. According to a study of 4,539 women, 28% of women attribute their discharge and light bleeding to pain1.

The color of the discharge can vary from pink or red to brown, which is normal.

Bleeding. Bleeding is usually compared to a normal menstrual cycle.

Episodes. Implantation bleeding may last less than 3 days and does not require treatment.

Implantation bleeding cramps resemble menstrual cramps, so some women mistake them and the presence of bleeding for the start of their menstrual cycle.

Also, a pregnant woman may notice white or milky vaginal discharge, which appears due to thickening of the vaginal walls, which begins almost immediately after conception. The growth of cells lining the vagina causes a discharge. These discharges are not dangerous, do not require treatment and can accompany a woman throughout her pregnancy.

Advice. If you experience a foul odor associated with your discharge, or a burning or itching sensation, be sure to tell your doctor so he can check for a bacterial or yeast infection.

It is important!

• The sperm is able to reach the egg pushed into the fallopian tube in about 2 hours, after which fusion occurs.
• One sperm, the first to penetrate the membrane, merges with the egg, after which it becomes impenetrable to others. A zygote is formed - a cell from which the embryo will begin to develop.

Implantation of fertilized egg.

Over the next few days, under the influence of muscle contractions and cilia of the mucous membrane, the fertilized egg moves towards the exit of the fallopian tube, that is, to the uterus. Around the same period, the process of fragmentation begins: the cells of the zygote begin to divide, but its overall size does not increase, each subsequent cell becomes smaller than the previous one. Having descended into the uterus, the zygote reaches the blastocyst stage in a few days, after which it gets rid of the membrane and is implanted inside the endometrium - the lining of the uterine walls. Under the influence of the hormone progesterone, aimed at maintaining pregnancy, the endometrium becomes thicker and surrounds the fertilized egg on all sides. Implantation allows you to protect the embryo and additionally nourish it with the secretion produced by the endometrial glands. Several days usually pass from conception to implantation, and the countdown of the first embryonic week does not begin with it, but with the formation of the zygote.

Nausea and vomiting

Morning sickness usually occurs between 4 and 6 weeks and, despite its name, can occur not only in the morning, but at any time of the day or night. There is no scientific basis for what exactly causes nausea, but hormones are definitely involved.

During the first trimester of pregnancy, many women experience morning sickness, which can range from mild to moderate to severe. May become more intense towards the end of the first trimester and often subsides by the beginning of the second trimester.

Morning sickness is probably the most well-known early sign of pregnancy, but not every pregnant woman experiences it!

Also, some pregnant women change their taste preferences: they either crave or have an aversion to certain foods so much that even the thought of what was once a favorite dish can cause a gag reflex.

Some women experience vomiting, nausea, cravings and food aversions throughout their pregnancy. But in most cases, these symptoms decrease around 13-14 weeks of pregnancy.

Clue

• Keep a bag of saltine crackers by your bed and eat a few before you get up in the morning.
• Drink plenty of water and stay hydrated
• Call your doctor if you cannot keep liquid or food down in your stomach.

Be sure to eat a healthy diet to ensure you and your developing baby get the nutrients they need. You can seek advice on this from your doctor.

It is important!

• You should see a gynecologist regularly in order, firstly, to detect pregnancy in time, and secondly, to track and eliminate the slightest irregularities.
• You can ask your gynecologist what other doctors you should visit. Endocrine disorders, metabolic problems, excess or underweight can affect conception.

Taking vitamins.

If your body doesn't have enough nutrients, your chances of getting pregnant may decrease. In the case of severe vitamin deficiency or lack of weight, menstruation, and with it ovulation, simply does not occur, that is, fertilization is impossible.

High blood pressure and dizziness

Blood pressure usually drops in the early stages of pregnancy. This may cause dizziness due to dilation of blood vessels.

High blood pressure during pregnancy is more difficult to detect. Almost all cases of hypertension during the first 20 weeks indicate health problems not related to pregnancy.

During your first visit to your doctor, he or she will take your blood pressure to help establish a baseline for a normal blood pressure reading.

Clue

• Do pregnancy-friendly exercise if you don't already.
• Learn how to regularly monitor your blood pressure
• Ask your doctor about dietary recommendations to help lower your blood pressure
• Drink enough water and eat regular snacks to prevent dizziness. Get up and sit down slowly - this helps.

Sensitivity to odors

There is little scientific evidence for the onset of odor sensitivity during the first trimester of pregnancy, which is one of the important signs in early pregnancy. It is important to know that sensitivity to odors can cause nausea and vomiting.

One scientific review looked at reports from 1922 to 2014 on the relationship between odors and pregnancy. 2 The researcher found a trend that women tend to rate odors as more intense during the first trimester.

What happens to the embryo at 2 weeks

A child at 2 weeks of pregnancy is not yet a fetus, but only one small cell that has just attached to the endometrium and is beginning to rapidly grow and divide. A genome is formed inside it - biological information that will determine the external image and developmental characteristics of the unborn child.

If a malfunction occurs and the set of chromosomes turns out to be incorrect, the zygote will not be able to attach to the wall of the uterus and will leave the body along with uterine bleeding. This will be a normal menstruation for you, but this is how the natural mechanism of selecting viable cells works.

Let us repeat that all this applies to the embryonic method of calculating gestational age.

Weight gain

Weight gain becomes more common towards the end of the first trimester. You can gain from 500 grams to 2 kilograms in the first few months. Calorie needs in early pregnancy are not much different from a normal diet, but they will increase as pregnancy progresses.

In later stages, pregnancy weight is distributed between:

• chest (from 500 grams to 1.5 kilograms);
• uterus (about 1 kilogram);
• placenta (about 500 grams);
• amniotic fluid (about 1 kilogram);
• increased volume of blood and fluid (about 2-3 kilograms);
• fat (from 2.5 to 4 kilograms).

Heartburn

Hormones can cause the valve between the stomach and esophagus to relax. This allows stomach acid to leak out, causing heartburn.

Before using medications for heartburn - so-called antacids that reduce the acidity of gastric juice by neutralizing hydrochloric acid - be sure to consult your doctor, as some of the antacids can negatively affect the health of the unborn baby.

Clue

• Prevent pregnancy-related heartburn by eating in several small meals instead of large ones
• After eating, try to sit upright for at least an hour to give the food more time to digest
• If you need antacids, talk to your doctor about your safety and the safety of your child.

It is important!

• There are ready-made vitamin and mineral complexes designed to increase the likelihood of conception. If no serious abnormalities requiring observation by a doctor are identified, you can use them.
• This point also applies to men: the state of the body directly affects the motility and viability of sperm, as a result of which they may lose the opportunity to reach the egg.
• If your doctor does not recommend vitamins in a particular case, it is better to listen to his words. It is also worth choosing supplements after consultation with a specialist.

Nutrition.

Problems leading to failure to conceive are often caused by insufficient or unhealthy nutrition. For pregnancy to occur, an optimal weight is necessary: ​​a lack of it leads to inhibition of reproductive processes, an excess is harmful due to possible endocrine disorders.

Other early pregnancy symptoms

Hormonal changes during pregnancy may cause other signs and symptoms:

• Bloating and constipation. Increased progesterone levels cause the bolus to pass through the intestines more slowly, which can contribute to constipation. Drink more water, exercise, and eat plenty of high-fiber foods.
• Mood swings. Estrogen and progesterone levels increase during pregnancy. This can affect your mood and make you more emotional than usual. Mood swings are common during pregnancy and can lead to depression, irritability and anxiety.
• Headaches and back pain. During pregnancy, some women report mild headaches and back pain.
• Dizziness and fainting.

Symptoms subside in the second trimester

During pregnancy, you may experience all of these signs and symptoms, and some women may only experience one or two. Many of these symptoms you experience in the first trimester will begin to disappear in the second trimester. Be sure to tell your doctor about any symptoms that interfere with your daily life.

Womenfirst

• Khachkuruzov, S. G. Ultrasound examination during early pregnancy / S. G. Khachkuruzov. — 7th ed. — Moscow: MEDpress-inform, 2021.
• Obstetrics and gynecology 4th edition revised 2019.
• Ministry of Health of the Russian Federation Clinical guidelines “Obstetric hemorrhage” 2016
• FSBI "Scientific Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov" DIAGNOSTIC ALGORITHM FOR BLEEDING / PAIN IN EARLY PREGNANCY Vikhareva O.N., Tetruashvili N.K., Voevodin S.M., Demidov V.N., Shmakov R.G., Yusupov K.F. 2015

RUS2124800-2 from 03/20/2020