The fourth week of pregnancy. 4 weeks pregnant

In obstetric practice, the fourth week of pregnancy means that your fetus is two weeks old. The embryo has already settled in your womb. Now a new life will develop inside you.

The fourth week of pregnancy. 4 weeks pregnant

The first 4 weeks of pregnancy pass almost imperceptibly for most women. Although in some cases, women have subtle symptoms and signs of pregnancy. Pregnancy symptoms in the 4th week are similar to those before menstruation. A woman may feel irritability, nervousness, and fatigue. In rare cases, taste preferences change and slight nausea appear — especially if you have an intolerance to certain smells.

What do women feel in the 4th week of pregnancy?

4 weeks pregnant pictures

Your emotional background may change. Some women are still unaware of their pregnancy; others have much more pronounced sensations. Tearfulness, unreasonable resentment, increased emotional reaction to irritants may testify about a new life in the womb.

Breast swelling

In the 4th week of pregnancy, you may notice swelling of your mammary glands. They become more sensitive. Women often think this is a premenstrual syndrome. In fact, your breasts swell in the 4th week of pregnancy due to hormonal changes in the body.


You are about 4 weeks pregnant, and if you don’t know you are pregnant, you wait for your mens to start, but it won’t! Menstruation delay is one of the symptoms and signs of pregnancy in the 4th week. In some cases, a pregnant woman may have a bloody discharge. This is so-called implantation bleeding, which occurs after the attachment of blastocyst — your 5−6-day-old embryo — to the uterine wall.

Discharges in the 4th week of pregnancy

You may have poor bloody discharge or more intense odorless whitish or transparent vaginal discharge in the fourth week. Consult your doctor if you have

  • intense bloody discharge;
  • brown discharge;
  • smelly discharge of any color;
  • any vaginal discharges accompanied by pain in your back or lower abdomen.

Your uterus in the 4th week of pregnancy

Different changes in the uterus happen in the 4th week of pregnancy under the influence of progesterone. Progesterone is the hormone that helps your embryo settle in the uterus. Due to active secretion of progesterone, the uterus swells, softens but doesn’t increase in size. A special thick mucous plug forms in the uterus. It will protect the baby’s dwelling and the baby itself from infections throughout its prenatal development.

Your baby in the fourth week of pregnancy

In the place, where your follicle released the fertilized egg a week ago, the so-called yellow body or corpus luteum has formed. It looks like a little bubble of liquid and is 1 to 3 cm in diameter. It produces the hormone progesterone, which supports the preservation of early pregnancy.

This week, the embryo will grow from 0.36 to 1 mm. Now your fetus is like a poppy seed. The fourth week is a very important stage in the development because at this time your future baby turns from a fertilized egg into a real embryo. In the second week of his life and in the fourth week of your pregnancy, the fetus looks like a disk. It consists of 3 layers of cells and is called a blastophyllum. Each layer has its own name and is the basis for various body parts of the baby.


The endoderm, or inner layer, is responsible for internal organs formation: liver, bladder, pancreas, respiratory system and lungs.

The mesoderm, or middle layer, is responsible for the muscular system, skeletal muscle, cartilage, heart, kidneys and sex glands, lymph and blood.

The ectoderm, or outer layer, is responsible for hair, skin, nails, tooth enamel, the epithelial tissue of the nose, eyes, and ears and eye lenses, nervous system (including the brain).

chorionСhorion is the outer embryonic membrane. It contributes to the creation of placenta. In place of your embryo’s attachment to the uterine wall, a vascular network begins to form. This network connects the mother and her fetus. The formation of the placenta will end only by the 12th week. Your baby gets oxygen and nutrients through it.

The amnion (amniotic membrane) is formed as a cavity in which the embryo lives. Later it will become the fetal bladder. The amnion produces amniotic fluid that protects the embryo from drying out and provides an optimal environment.

The yolk sac is responsible for hematopoiesis in the embryo up to 7−8 weeks of development.

What to do in the 4th week of pregnancy?

4 week fetus picture

  • Pregnancy test

Though there is only a slight increase in human chorionic gonadotropin in the urine, a pregnancy test can sometimes «recognize» an already existing pregnancy.

  • Ultrasound

Ultrasound in the fourth week of pregnancy can show a yellow body, which gradually increases in size, nourishing the embryo before the formation and proper functioning of the placenta. In addition to the yellow body, highly sensitive ultrasound can detect an embryo in the uterus when you are 4 weeks pregnant. Ultrasound surveys are extremely rare in this phase, as most women only suspect their possible pregnancy.

  • Analyses and tests

A pregnancy test can’t always determine a four-week pregnancy. However, blood tests for hCG can quite clearly give you the answer, because at this stage shells of the embryo secrete great amounts of hCG. Its level in the blood becomes a proof of pregnancy. The same is true about progesterone, which is produced by the yellow body.

  • Fever and cold at 4 weeks pregnant.

Cold and fever are very dangerous in the 4th week of pregnancy. During this period, the embryo is extremely vulnerable to any, even most insignificant factors. Still, you shouldn’t panic, as psychological stress can be even more dangerous for your baby. If you have caught a cold but your body temperature isn’t high, simply avoid being in crowded places and stay at home for a few days. Rinse the nose with salt water, drink plenty of water or warm tea with honey, take cough syrup with licorice root.

If your temperature in the 4th week of pregnancy is 38 degrees and above — it is very undesirable for the embryo’s development. Fever impacts negatively on the development of the baby and may even lead to miscarriage. Therefore, it is necessary to strengthen the immune system before getting pregnant.

  • Alcohol in the fourth week.

Alcohol is extremely dangerous when you are 4 weeks pregnant. It can cause irreversible developmental abnormalities in the fetus. Alcohol can become the cause of spontaneous abortion. As it was mentioned above, the process of organs development is unusually active at this time, so drinking alcohol in the 4th week of pregnancy has a significant damaging effect on this process. Alcohol is a highly toxic substance that causes a disruption in the formation and development of the embryo. In high doses, it dramatically increases the risk of giving birth to a child with developmental disabilities and all sorts of anomalies. Therefore, those moms, who want a healthy and strong child, should completely exclude alcohol from their diet since the first weeks of pregnancy or even a few months before pregnancy.

  • What to eat when you are 4 weeks pregnant

At this time, the embryo is very susceptible to any negative factors. One of the possible negative factors is the lack of vitamins and minerals that are necessary for normal formation and development of the baby. That’s why healthy and balanced diet is extremely important. Try to eat only natural products and foods containing sufficient amounts of vitamins and minerals. Smoked meat, canned foods, fatty and salty foods, candies should be left in the past. It is desirable to exclude all «artificial» products with dyes, flavorings, food additives, and sweet or colored soda from your diet. Eat more lean meat, dairy products, cereals, vegetables and fruit, fresh and natural food. You should also forget about diets and fasting days during this period: the lack of nutrients and minerals can be detrimental to your baby.

4 weeks pregnant ultrasound pictures

4 weeks ultrasound picture

4 week sonogram pictures

4 weeks pregnant ultrasound pictures

pictures of 4 weeks pregnant belly

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