Its growth accelerates: at the end of this first month of pregnancy, the size of the embryo at 4 weeks is 5 mm. Its general shape has also evolved: the embryonic disc, composed of three layers, has rolled up to become a cylinder with a fold at each end, one corresponding to the head, the other to the tail – which it will soon lose. The overall structure of the body takes shape.

It is also during this 4th week of pregnancy (6 weeks) that a key stage in the development of the embryo begins: organogenesis. The main organs of the fetus are put in place:

· A primary intestine takes shape as well as an outline of the liver, pancreas and gall bladder;

· At the cardiac level, the two primitive tubes merge and present in certain places dilations: it is the outline of the heart and its atria and ventricles;

· Three bulbs appear in the future brain;

· The spinal cord is already running all the way down the future back of the fetus;

· The buds of the thyroid and pituitary glands are formed;

· The sense organs are put in place with a draft of the inner ear, the eye and a tongue bud;

The buds of the arms appear;

The sex organs are not yet present but the sex cells start to migrate to the development site of the ovaries or testes.

The amniotic cavity grows and now surrounds the 4 week old fetus. The umbilical cord is not yet fully formed, but it already connects the embryo to the outer part of the egg. With the development of the baby’s blood vessels, everything is put in place for the maternal-fetal circulation to begin via the umbilical cord and the placenta, now formed of intervillous chambers filled with maternal blood.

In 4 weeks of pregnancy, the egg has passed from an original cell – the zygote, born from the fusion between the male and female gametes – to several million cells perfectly organized between them.

Periods are two weeks late. The future mother is at 6 weeks of amenorrhea (4 SG). The pregnancy is therefore probably known. Especially since the first signs of pregnancy, still discreet or even absent during the 3rd week of pregnancy, are accentuated under the effect of pregnancy hormones:

• the chest has grown, it is tense. The nipples are more prominent, the areolas darker and dotted with small glands, the Montgomery tubercles;
• fatigue is sometimes present in the morning and can lead to drowsiness during the day;
• nausea appears or worsens.

However, these pregnancy symptoms are not systematically present in all pregnant women in the 1st trimester. Some, who are lucky, will never know what the ailments of pregnancy are. Moreover, if pain persists, no medication should be taken without the advice of a doctor. 

From the 4th week of pregnancy (6 weeks), the uterus begins to grow: it is now the size of a tangerine. Not enough for the pregnancy to be visible from the outside, but enough to cause little inconvenience to the mother-to-be:

• tightness in the lower abdomen due to working ligaments;
• frequent urges to urinate due to the pressure of the uterus on the bladder.

At the end of this 4th week of pregnancy (6 weeks), a pregnant woman’s appetite may increase and in this case, she may gain weight. Conversely, she may be bothered by nausea and therefore have a suppressed appetite and lose pounds. Nausea can be alleviated by the absorption of ginger tea or homeopathy. You should also avoid cooking foods that could be the cause of her nausea. If the pregnant woman does not have much appetite, it is not very serious, as long as she is not deficient: it is important to inform her doctor, however. The 4-week-old embryo feeds on the placenta and multiple blood vessels. There he finds the essentials to cover his nutrient and oxygen needs. 

However, the future mother, even at 6 weeks of amenorrhea (4 SG), must consume certain foods to prevent possible dietary deficits. She needs folic acid and vitamins. They are found in fruits and vegetables, raw or cooked. Care must be taken to wash them carefully, to avoid toxoplasmosis: a parasite that is dangerous for the embryo. Steaming is recommended, to keep maximum benefits. Regular overeating is to be avoided. The consumption of bad fats (cakes, sweets, fast food…) is not recommended during pregnancy, even if the pregnant woman can allow herself a culinary pleasure from time to time. 

The future mother must continue to have a food hygiene, thanks to balanced meals and good hydration.

À 6 weeks of amenorrhea (4 SG), and if it is not already done, it is time to make an appointment with your gynecologist or a midwife for the first prenatal visit (before 15 WA). This is an opportunity to think about the type of follow-up you want for this pregnancy: follow-up with your usual gynecologist, in town; at the hospital where you know you already want to give birth; more personal follow-up with a midwife in the office. It will always be possible to change thereafter, but it is better to ask yourself these kinds of questions early, especially as in some maternities, registration must be done from the first month of pregnancy.

One month pregnant, it is common to have mixed feelings. There is the joy of being pregnant of course, but also the worry that this news, which heralds a great change in life, can give rise to. In addition, during the 1st trimester, the hormonal climate, nausea of ​​pregnancy and fatigue do not help the mother-to-be to feel her best. The fear of miscarriage can also be very present in some expectant mothers, especially in the event of a history of this pregnancy accident. Do not hesitate to speak about these different feelings to an attentive ear.

The pregnant woman can keep a pregnancy notebook week by week in which she notes her different impressions, her questions and even her doubts. It helps him release and control his emotions. She will feel less overwhelmed. In addition, during a medical appointment, she will not forget to ask any questions.