4 weeks pregnant, what happens to the fetus and what the woman feels

The child’s age is the second week (one full), pregnancy is the fourth obstetric week (three full).

So, four weeks of waiting for the baby. What does this mean?

The content of the article:

What does the term – 4 weeks mean?

Very often women miscalculate their pregnancy. I would like to clarify a little that the fourth obstetric week is the second week from conception

If conception occurred 4 weeks ago, then you are in the 4th week of the actual pregnancy, and in the 6th week of the obstetric calendar

Signs of pregnancy in the 4th obstetric week of pregnancy – the second week after conception

There is still no direct evidence of pregnancy (delayed menstruation), but a woman is already beginning to detect such signs as:

Although it is worth mentioning that all these symptoms are not unequivocal and indisputable signs, since a woman can experience all this before menstruation.

If you think that you conceived two weeks ago, it means that you think that you are already pregnant, and you know the date of conception. Sometimes women know the exact date because they regularly measure basal temperature, or do an ultrasound scan in the middle of the cycle.

At the 2nd week after conception, the estimated time for the onset of menstruation occurs. It was at this time that many of the women begin to guess about their interesting situation and buy pregnancy tests. On this line, the test very rarely shows negative, because modern tests are able to determine pregnancy even before the delay.

At this time (2 weeks) the future baby has just been implanted into the wall of the uterus, and is a small lump of cells. In the second week, spontaneous miscarriages quite often occur, which are not taken into account, because very often they do not even know about them.

A slight delay in menstruation, spotting and unusual brown spotting, very profuse or prolonged periods – these signs are often mistaken for a woman’s regular period, without even knowing that she may be pregnant.

At 1-2 weeks after ovulation, the signs are very weak, but most often the expectant mother already guesses, and sometimes knows.

In the 2nd week from ovulation, the symptoms that appear are due to the rather high level of hormones that preserve the fetus.

Feelings in the expectant mother in the 4th obstetric week

As a rule, nothing in a woman’s condition suggests pregnancy, because the most obvious sign – a delay – is not yet available.

4 weeks is not the end of the cycle for a larger number of women, and thus the woman cannot yet know about her interesting position.

Only drowsiness, increased fatigue, a sharp change in mood, soreness of the mammary glands can suggest the onset of this wonderful period, like waiting for a baby.

However, each organism is individual, and in order to understand feelings of different women at 4 weeks, you need to ask them themselves (reviews from the forums):


Unbearable pain in the mammary glands, terribly pulls the lower abdomen, I have no strength, I became very tired, I do not want to do anything, I am angry for no reason, crying, and this is only 4 weeks. What will be next?


I was very nauseous in the 4th week, and my lower abdomen was pulling, but I assumed it was premenstrual syndrome, but it was not there. A couple of days after the delay, I made a test, and the result was very pleased – 2 strips.


Term – 4 weeks. I have long wanted a child. If it weren’t for the constant morning sickness and mood swings, it would be just perfect.


I am very happy about my pregnancy. Of the signs, only the chest hurts, and it feels like it swells and grows. Bras will have to be changed soon.


The test showed 2 strips. There were no signs, but somehow I still felt that I was pregnant. It turned out that it is. But I am very upset that my appetite rises like hell, I have already gained 2 kg, I constantly want to eat. And there are no more signs.

What happens in the mother’s body in the second week of pregnancy – the fourth obstetric week?

First of all, it is worth mentioning the external changes taking place in the body of a happy newly-made mother:

  • The waist becomes a little wider (only a couple of centimeters, no more), although only the woman herself can feel this, and the people around her cannot even notice with an armed glance;
  • The chest swells and becomes more sensitive;

As for the internal changes in the body of the expectant mother, there are already enough of them:

  • The outer layer of the embryo begins to produce chorionic gonadotropin (hCG), which signals the onset of pregnancy. It is for this week that you can do home rapid test, which and notify the woman of such a pleasant event.
  • This week, a small bubble forms around the embryo, which fills with amniotic fluid, which, in turn, will protect the unborn baby until delivery.
  • This week, the placenta (afterbirth) also begins to form, through which further communication of the expectant mother with the child’s body will take place.
  • An umbilical cord is also formed, which will provide the embryo with the ability to rotate and move in the amniotic fluid.

It should be clarified that the placenta is connected to the embryo through the umbilical cord, which is attached to the inner wall of the uterus and functions as a separation of the mother’s and baby’s circulatory system to avoid mixing of mother and baby’s blood.

Through the placenta and the umbilical cord, which are formed at 4 weeks, further up to the very birth, the embryo will receive everything it needs: water, minerals, nutrients, air, and also discard processed products, which in turn will be excreted through the mother’s body.

Moreover, the placenta will prevent the penetration of all microbes and harmful substances in case of mother’s ailments. The placenta will be complete by the end of 12 weeks.

Fetal development in the 4th week

So, the first month is almost over and the baby is growing very quickly in the mother’s body. In the fourth week, the ovum becomes an embryo.

The embryonic vesicle is very small, but consists of a very large number of cells. Although the cells are still very small, they know very well what to do next.

At the same time the inner, middle and outer forms of the germ layers are formed: ectoderm, mesoderm and endoderm… They are responsible for the formation of vital tissues and organs of the unborn child.

  • Endoderm, or the inner layer, serves to form the internal organs of the unborn baby: liver, bladder, pancreas, respiratory system and lungs.
  • Mesoderm, or the middle layer, is responsible for the muscular system, skeletal muscle, cartilage, heart, kidneys, sex glands, lymph and blood.
  • Ectoderm, or the outer layer, is responsible for hair, skin, nails, tooth enamel, epithelial tissue of the nose, eyes and ears, and eye lenses.

It is in these germ layers that the potential organs of your unborn baby are formed.

Also during this period, the spinal cord begins to form.

Photo and appearance of the embryo at the 4th week

At the end of the fourth week, one of the most important stages of intrauterine development, blastogenesis, ends.

What does a baby look like in the 4th week? Your future baby now resembles a blastula in the shape of a round plate. The “extraembryonic” organs, which are responsible for nutrition and respiration, are intensively formed.

By the end of the fourth week, some of the cells of the ectoblast and endoblast, tightly adjacent to each other, form the embryo rudiment. The embryo rudiment is three thin layers of cells, different in structure and functions.

By the end of the formation of the ectoderm, exoderm and endoderm, the ovum has a multilayer structure. And now the baby can be considered a gastrula.

So far, no external changes have taken place, because the period is still very small, and the weight of the embryo is only 2 grams, and its length does not exceed 2 mm.

In the photos you can see what your future baby looks like during this period of development.

Ultrasound, pregnancy 2-3 weeks
Ultrasound, pregnancy 2-3 weeks

Photo of the unborn baby in the 2nd week of pregnancy

Fetus 2 weeks pregnant - photo
Fetal development – 2 weeks

Ultrasound in the 4th obstetric week

An ultrasound scan is usually done to confirm the fact of pregnancy and its duration. Moreover, ultrasound may be prescribed if there is an increased risk of ectopic pregnancy. Also, at this time, you can determine the general condition of the placenta (in order to avoid its detachment and subsequent miscarriage). Already in the fourth week, the embryo can please its new mother with the contraction of its heart.

Pregnancy 4 weeks - ultrasound
Ultrasound in the 4th week

Video: What Happens in Week 4?

Video: 4 weeks. How to tell your husband about pregnancy?

Recommendations and advice for the expectant mother

If you have not done this before, then now is the time to change your lifestyle.

So, the following tips will help you and your baby-to-be stay in good health:

  • Review your menu, try to consume foods that contain the highest amount of vitamins. Getting all the necessary vitamins plays an important role in the life of every person who wants to stay healthy, and even more so in the life of a newly-made expectant mother. Avoid flour, fatty and spicy foods, and coffee as much as possible.
  • Eliminate alcohol completely from your diet. Even a small dose of alcohol can cause irreparable harm to you and your unborn baby.
  • Quit smoking, moreover, try to be near smokers as little as possible, because secondhand smoke can harm no less than active. If your household members are heavy smokers, persuade them to smoke outdoors, as far away from you as possible.
  • Try to spend as little time as possible in crowded places – thereby significantly reducing the risk of contracting infectious diseases that are detrimental to the fetus. If it so happens that someone from your environment still managed to get sick – arm yourself with a gauze mask. For prevention, also do not forget to add garlic and onions to your diet, which effectively fights all possible diseases and does not harm your baby.
  • Talk to your doctor about taking a vitamin complex for expectant mothers. WARNING: avoid taking any medication without first consulting your doctor!
  • Do not get too carried away with X-ray examinations, especially in the abdomen and pelvis.
  • Protect yourself from unnecessary stress and anxiety.
  • Be considerate of your pets. If you have a cat in your home, do your best to reduce its exposure to street animals and limit it from catching mice. Yes, and try to shift your responsibilities in caring for the cat onto your husband. Why, you ask? The fact is that many cats are carriers of Toxoplasma, with the initial ingestion of which the body of the expectant mother will be susceptible to a disease leading to genetic defects in the fetus. The best option is to have your cat checked out by a veterinarian. If a dog lives in your house, pay attention to timely vaccinations against rabies and leptospirosis. In general, the recommendations for communicating with a four-legged friend are the same as with a cat.
  • If week 4 falls on the hot season of the year, exclude dishes that include overwintered potatoes to avoid birth defects in the baby.
  • Be sure to include hiking in your daily routine.
  • Consider the possibility of exercising. They will help you stay toned and strengthen your muscles. There are special sports sections for pregnant women that you can visit, but calculate your possibilities so as not to overload yourself.
  • Rub olive oil into your belly skin now to help prevent stretch marks after childbirth. This method can prevent this unpleasant and so common phenomenon in advance.

Compliance with these recommendations will help you easily endure one of the most crucial periods in your life and give birth to a strong, healthy baby.

Previous: Week 3
Next: Week 5

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