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4th week of pregnancy

4th week of pregnancy


In obstetrics, the gestational age is considered from the first day of the last menstruation and does not correspond to the embryonic period. Thus, the 4th obstetric week is the second week after the conception of a child.

How the fetus develops during this period and how the woman’s condition changes, read the article.

Fetal development in the 4th week of pregnancy

The embryo is placed inside the mucous membrane of the organ to get further nourishment and oxygen from the mother. This is called implantation, which normally happens on the 7th or 8th day after conception.

Such important structures are formed as:

  • Chorion: It is the outer shell of the fetal egg. Closer to the 12th week, part of the chorion is transformed into the fruiting part of the placenta. The placenta will provide all the needs of the fetus: oxygen supply, nutrition and removal of unnecessary substances. Even now, the first blood vessels are formed in the villi of the chorion, through which the exchange of substances between mother and child occurs.
  • Yolk sac: in the early stages, it performs a trophic function. It will function for up to 7-8 weeks.
  • Amnion: which is filled with amniotic fluid.

If you attempt to use ultrasound at the present time and take a picture, you won’t be able to detect the embryo since it is too minuscule. Most up-to-date machines can only establish the presence of a fetal egg in the uterus, which resembles a tiny grain and is no more than 1 mm in size. It will be possible to observe the embryo in 1-2 weeks.

The embryo begins to develop actively during the 4th to 5th week of pregnancy. This process involves the formation of three germ layers, which are the ectoderm, mesoderm and endoderm. The ectoderm will source the skin, teeth, hair and nails, and the nervous system. The middle layer will give rise to the spine, skeletal muscles, blood vessels, blood, sex glands and most internal organs. Finally, the inner layer will form the digestive tract, lungs, liver and pancreas.

In the 6-8th day after conception, the production of human chorionic gonadotropin (hCG) starts and this hormone can be detected in the blood and urine of pregnant women. Additionally, growth factors that are essential for the further development of the embryo are produced during this period.

Furthermore, by the end of the 4th week, the embryo’s nervous system is in the process of forming; the neural plate is laid, then the neural groove and then the tube, which evolves into the brain and spinal cord. For the normal development of the nervous system, it is required to have adequate amounts of vitamin B9 (folic acid). For this reason, gynecologists suggest taking folic acid even before conception.

4 week pregnancy symptoms

At this time, some expectant mothers do not notice any signs of pregnancy. Some women notice the first signs of pregnancy:

  • Unreasonable mood swings.
  • Fatigue, lethargy, drowsiness, less often – insomnia.
  • Enlargement and sensitivity of the mammary glands.
  • Increased or decreased appetite.
  • Addiction to unusual tastes, desire to try unusual food.
  • Intolerance to strong odors.

In the early stages of pregnancy, some women may experience symptoms of toxicosis such as nausea, vomiting, and profuse salivation. Typically, these symptoms occur around the 5 to 6-week mark. Many women may also experience increased natural vaginal discharge, which is generally thicker and more plentiful. It is important to note that any unpleasant smell, itching, or discomfort should be discussed with a doctor. Some women may not feel any symptoms in the 4th week, with the only sensation being slight weakness and tenderness in the breasts.


Pregnant women may be surprised to learn that they are still menstruating, as menstruation cannot occur during pregnancy. However, if there is any spot, it should be taken as a warning sign. This is likely due to a hematoma, a blood collection between the fetus and the uterine wall. 

The reasons may be different:

  • The fetus was originally not viable and now the body rejects it.
  • There is a deficiency of progesterone or an increased level of androgens.
  • Women who have had viral or bacterial infections during the first few weeks of pregnancy may be at risk of fetal death or a missed pregnancy.

Stomach ache

Abdominal pain at four weeks pregnant is not unusual. This is usually caused by the uterus expanding, which leads to stretching of the ligaments and what is commonly referred to as “pulling pains”. Additionally, this may be due to the digestive system being affected by the hormonal changes in a woman’s body, resulting in heartburn and other discomforts. In some cases, abdominal pain can be a warning sign of complications during pregnancy, such as a potential miscarriage, ectopic or missed pregnancy, and is often accompanied by intense, acute pain.

Brown discharge

Typically, during pregnancy, vaginal discharge should remain similar to what it was before, i.e., clear and white with a neutral or slightly acidic smell, although the amount tends to increase. If there is a change in the color or smell of the discharge, it is important to alert a doctor. Brown discharge could indicate a source of bleeding inside the woman’s body, which should be identified and, if possible, remedied.

Alarming symptoms in the 4th week of pregnancy

At the start of pregnancy, many women experience mild pulling or cramping sensations in the lower abdomen. This is often mistaken for the beginning of their period but is actually a result of their body adjusting to the new conditions. If the pain worsens, it is important to seek medical help to avoid possible complications.

Another sign of something potentially being wrong is the presence of bloody discharge. During the 4th week, this could indicate implantation, and it may be light, spotty, or red or brown. It should disappear within 1-2 days. 

However, suppose the pregnancy test is positive and the bloody discharge continues. In that case, it is necessary to consult a doctor as it may be a sign of a miscarriage, ectopic pregnancy, or other complications.

Blood issues

At the beginning of pregnancy, such discharge may indicate successful embryo implantation. But in general, spotting during pregnancy is a bad sign. Losing time in this situation can be deadly for both mom and baby. The appearance of blood in the discharge can signal various possible problems:

  • About the threat of miscarriage.
  • Up to 12 weeks – about the presence of a retrochoir hematoma (a blood cushion between the uterus wall and the tissue that nourishes the baby): the larger the hematoma, the less chance of survival the child has.
  • About placenta previa.
  • About detachment of a normally located placenta, which disrupts the oxygen supply to the fetus, which is dangerous for his life.

If you notice blood on your underwear, do not waste time and call an ambulance.

Sometimes pregnant women may notice spotting after intercourse. Most often, the cause is an injury to the mucosa, but inflamed erosion and even a tumor can also bleed. And this is also a reason to see a doctor as soon as possible.

pink discharge

This shade means there is probably bleeding in the body, which can be dangerous during pregnancy. Often pink discharge provokes sexually transmitted diseases. A pregnant woman should seek medical advice immediately to avoid any potential negative impacts on her baby.

How to find out about the pregnancy in the 4th week

If you have missed your period and want to check if you are pregnant, you should take a quick pregnancy test. This test detects HCG, a hormone produced during pregnancy, in the urine. It is usually 98% accurate after a missed period. 

If the test is positive, you must see a doctor and register for pregnancy. If it is negative, you should retake the test after two days. If the second test is still negative and your period has not arrived, you should make an appointment with a gynecologist for an examination.

Sometimes the test gives a negative result for other reasons:

  • The test is outdated or damaged (for example, stored in inappropriate conditions).
  • The test was performed incorrectly. It is recommended to check in the morning with the first portion of urine. Urine must be in contact with the test system for at least 5 seconds. The result should be evaluated after 3-5 minutes. Read the instructions carefully.
  • The gestational age was incorrectly determined. This happens with an irregular menstrual cycle and some gynecological diseases.
  • Ovulation occurred later than anticipated. Generally, the 4th week of pregnancy is equivalent to the 2nd week from conception – since many women with a 28-day cycle have the egg mature in the middle of the cycle, on the 12-14th day. However, sometimes ovulation could take place later. The hCG level would be too low to be detected by the test.

Do’s and Don’ts at 4 weeks pregnancy

The first weeks of fetal development are extremely important, and in the fourth week the baby is attached to the wall of the uterus so a woman should behave as carefully as possible and know what can and cannot be done at such a time.

Do’s at 4 weeks pregnancy

  • Monitor health and proper sleep patterns since the immunity of the mother’s body depends on this.
  • Take vitamin complexes recommended by a doctor.
  • Diversify nutrition, and add natural sources of vitamins and minerals.
  • Spend more time in the fresh air, and take walks before bed.
  • Lead an active lifestyle, do fitness, and go to the pool.
  • Switch to light work if there is an influence of teratogenic production factors.
  • Undergo an ultrasound examination and take the first photo of the baby.

Don’ts at 4 weeks of pregnancy

  • Lift weights, give the body power loads, and perform exercises with weight in the gym.
  • Drink alcohol, drugs, and smoke.
  • Be in the company of patients since chickenpox, rubella or other infectious diseases can terminate the pregnancy.
  • With in vitro fertilization, sexual activity is prohibited.
  • Take medications without consulting a doctor.
  • Use folk remedies and homeopathy without the knowledge of the gynecologist.
  • Undergo an X-ray examination (except in emergency cases).
  • Contact with aggressive chemicals.
  • Take hot baths, use enemas, and douche.

Proper nutrition for 4 weeks pregnancy

Pregnancy forces a woman to change her nutritional preferences and habits, primarily for the successful development of the fetus. Hence, doctors insist on thoroughly reviewing the diet and introducing healthy foods that will saturate the mother’s body with useful vitamins and minerals.

At the 4th week of pregnancy, it is recommended:

  • It is recommended to exclude heavy meals that provoke constipation and are digested for a long time in the stomach. Fatty foods also have the same negative properties – it is better to replace them with easily digestible carbohydrates and proteins and add fiber to the diet – vegetables and fruits according to the season.
  • If the morning breakfast failed, and the woman was tormented by toxicosis, you should not postpone eating or refuse it. After half an hour, eat a lighter dish – scrambled eggs, cottage cheese, cheese.
  • To combat constipation, you do not need to overeat protein foods; fruits and vegetables, berries, and bread with bran will contribute to the formation of soft feces.
  • Having learned about pregnancy, you should not eat for two – from this. You can only gain excess weight and complicate the process of bearing a baby and childbirth. A woman must only increase and diversify her diet to give her and her child nutrients.
  • Do not forget about the drinking regime – you need to drink about one and a half liters of liquid per day, it can be clean water, fruit drinks, juices and compotes;
  • Soda, coffee, and alcohol should be excluded from the diet – these liquids will harm both the mother and the child. When replacing coffee with herbal tea, be careful – some herbs can increase the tone of the uterus, so it is better to consult a doctor in advance and study the composition of the tea.

Checklist for the 4th week of pregnancy

  1. Take a pregnancy test if there is a delay in menstruation.
  2. Visit a Prenatal care clinic and confirm pregnancy.
  3. Give up alcohol and smoking.
  4. Avoid stress and emotional overstrain.
  5. Take vitamins recommended by the doctor.
  6. Change the menu, and add healthy products.
  7. Make sure not to be in an epidemic environment.
  8. Do not contact animals.
  9. Keep a diary and monitor your weight and your feelings.
  10. Eliminate caffeine, fatty foods, and simple carbohydrates.
  11. Balance the daily routine, and take enough time to sleep.
  12. Do not come into contact with harmful chemicals.

Can you dye your hair during pregnancy?

It’s best to avoid close contact with chemicals when you’re expecting a baby. Usually the ban on hair dye is due to several reasons:
1. The woman and the fetus can be harmed by the chemicals that make up the dye, for example, ammonia, hydrogen peroxide, paraphenylenediamine, and resorcinol.

2. The condition of a pregnant woman can be affected by an unpleasant odor that most paints have. It can provoke nausea and vomiting, especially in the first trimester.

3. Due to hormonal fluctuations, the structure and oiliness of the hair change, and you can get a completely unexpected shade.