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Pregnancy by week
Medical expert of the article
Last reviewed: 06.07.2025
Rarely does a woman have the good fortune to learn about her pregnancy in the first days of its onset. As a rule, the manifestation of signs begins 2-5 weeks after fertilization. And as soon as it became known that the "miracle has happened", women begin to count the pregnancy by weeks, days, hours, minutes. Normal gestation lasts nine months, but in obstetrics, it is customary to count the terms by weeks.
Most people around a pregnant woman treat her as if she were sick with a terrible disease. Everyone thinks that she is very fragile, vulnerable and helpless. Of course, a woman needs help and support, but you still shouldn’t completely protect and patronize her. If we consider the bearing of a child by weeks, then it is at 10-15 weeks that the expectant mother needs frequent walks, positive emotions, and a sedentary, passive lifestyle and a bad mood are equally contraindicated.
However, this condition has its own symptoms, which are more or less constant for all women without exception:
- the absence of a menstrual cycle is the very first and most obvious sign of conception;
- drowsiness, fatigue, general malaise;
- slight nausea, sometimes severe in the morning, at different stages after conception can develop into vomiting;
- changes in gastronomic preferences and inadequate reactions to familiar smells;
- frequent urge to urinate, not always productive;
- at later stages, constipation and bloating appear;
- formation of pigment spots localized on the face.
Despite the clearly expressed symptoms, it makes no sense to classify the condition after fertilization as a disease, because for the female body it is natural, which is confirmed by all the internal organs, which, without any special changes in their structure or in the functions they perform, “allow” the fetus to develop successfully.
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What are trimesters?
It is important to count pregnancy by weeks because of the rapid development of the fetus. However, obstetricians and gynecologists also count it by trimesters. There are three of them during pregnancy. A trimester is three consecutive months. That is, one trimester is four weeks. Why such complications, you ask? We have already partially explained, saying that the development of the embryo is rapid, and in order to prevent failures in its formation, weekly observation is necessary. There is no need to go to the doctor every week, but a woman should know for herself what is happening in her body and in what week.
Pregnancy by weeks: 1-12
From the first to the 12th week, life is filled not only with positive emotions, but also with considerable worries. There are many reasons for this. In the first three months, or if you count pregnancy by weeks - the first 12-16 weeks, there is a high probability of miscarriage. That is why it is so important for expectant mothers to listen carefully to their bodies and try to be as careful as possible during this period.
Formation of the fetus
The life that has arisen in these weeks has the form of several cells that actively divide, producing a hormone called hCG ( human chorionic hormone ). If a woman suspects something is wrong and, first of all, decides to take an hCG test, then the indicators, in the case of the presence of a fetus in the womb, will be equal to any three-digit indicator.
The fetus begins to "lay down" all of its internal organs, including the formation of the nervous system, the separation of the heart, arms and legs. Any disturbance in the woman's body during this period can cause abnormal fetal development. At the end of the first month, the embryo is tiny, only 4 mm. In the second month, the embryo's brain is actively developing, a heartbeat appears, and the fetus's size reaches 2-3 cm by the end of the eighth week.
Looking at pregnancy week by week, you can see that 9-10 weeks add another 1-2 cm to the growth of the embryo, the digestive organs appear, the convolutions of the brain are isolated. 11-12 weeks - the liver begins to work, bile is formed, the heart has an almost complete, four-chamber structure. The fetus's fingers and toes are already visible, and the face can be seen. At 14-16 weeks, the fetus has already "grown" 10 centimeters.
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Pregnancy by weeks: 13-24
From the 13th to the 24th week, the most exciting behavior of the fetus appears, which is expected not only by the mother. Fathers also anxiously await the moment of fetal movement. Having calculated the pregnancy by weeks, this moment should be expected somewhere between the eighteenth and twenty-first of them.
Movements and jolts are a sign that the fetus's muscles and ligaments have begun to develop. Fingerprints begin to form on the fingers, the child receives a fingerprint identifier, receives his first personal code, which will make him unique in adulthood, because fingerprints never repeat their pattern in different people.
During these weeks, the fetus's growth increases rapidly. So, if at 4 months it is 15 cm, at 5 months - 20, then at six months it is already 30 centimeters. Along with growth, muscle mass is also gained. The musculoskeletal system continues to develop, the genitourinary system is characterized by the development of the kidneys and the beginning of their work. Urine is produced, and the sebaceous glands begin to work. By the end of this period, the child acquires soft fluff on the body, active movements are replaced by passive behavior (at these moments, the child sleeps). The facial muscles of the face are also well developed by this time, and this allows you to see, during the ultrasound procedure, how the baby frowns or smiles. There may be moments when the child hiccups or coughs.
With the development of medical technology, observing pregnancy week by week has become incredibly interesting, both for the parents themselves and for doctors. Modern ultrasound machines allow you to see a full-scale, color image, where you can see even the smallest details and nuances. This is no longer a black and white outline and incomprehensible, but a “real” video about the life of a baby in the womb.
The child receives all the necessary development, but it is not enough to support the life of a small organism, in case of premature birth. The viability of a six-month fetus, outside the mother's body, is very low. Although medicine knows of cases of births at 6 months with a favorable outcome. But these are isolated cases, and premature babies are kept on artificial life support devices for several months. They are, as it were, carried to term by means of special incubators, where the necessary temperature regime is provided to children. So, despite the high level of technical equipment of modern medical centers, for a child, there is nothing better than to spend the entire allotted time in the mother's tummy.
Pregnancy by weeks: 25-36. Expectations and worries
Pregnancy by weeks, namely from 25 to 36, passes in excitement and anxiety, because the baby is already developed enough and can be born at any moment, even despite the fact that there are 2 months left until the end of the term. Having counted the pregnancy by weeks, and approaching the 28th, the baby can decide to be born. Babies born at this time are quite viable, despite the fact that their body has some physiological deficiencies. For example, a seven-month fetus has not yet developed subcutaneous fat, due to which the body's thermoregulation is impaired. In other words, the newborn's body cannot maintain body temperature at a constant level. This threatens sudden hypothermia. Premature babies born at seven months must be under constant medical supervision. In addition to the lack of thermoregulation in the body, the lungs are not sufficiently developed, and the child cannot breathe on his own. To ensure all necessary vital functions, such children are placed in incubators.
Let's assume that the baby has decided to stay in the womb for the entire period and receive full physical, physiological and even initial psychological development. The eighth month, or the thirty-second week, if you count pregnancy by weeks, is completely dedicated to preparing the child for birth. The sense organs begin to show their activity. The child hears and is able to respond to pain. In the eighth month, the fetus weighs 2 - 2.5 kg, the height approaches 45 centimeters. Of course, all indicators of growth and weight, at different stages of development, are individual for everyone. There are babies who are born at 9 months weighing 2.5 kg, and only 47-50 cm tall. Everything depends on the constitution of the parents, the correctness of the fetus's development and many other indicators. Therefore, the text provides average statistical indicators that should be used as a guide, but it is not necessary to take them as a standard of comparison.
And finally, the ninth month. The fetus is preparing for birth continuously and “in full swing”. The baby’s lungs are completely ready for independent breathing. They are well developed, a special fatty substance has formed in them, which envelops the alveoli (the smallest air bubbles that make up the lungs) preventing them from sticking together. The fluff “comes off” the newborn’s skin, remaining only on the head, the skin becomes smooth and elastic. The baby takes a body position that facilitates the unimpeded course of labor, the head descends into the pelvic area. The baby is ready to come out.
Correct behavior of mother - healthy development of baby
When a future mother begins to count her pregnancy by weeks, she, of course, knows what she can eat and what she can't, what she can do and what she should avoid. Surely everyone knows that during the formation of the fetus's skeletal system, calcium, as the main building block, passes from the mother's body to the child's body. The fetus's skeleton is formed, and the mother's teeth are damaged, her nails are broken, her hair falls out, and the bone structure of her own skeleton suffers. At any stage, it is worth following simple rules that will help the baby be born healthy and full-fledged, and the mother's body will not suffer from a lack of vital substances and microelements.
1-13 weeks
- complete rejection of bad habits;
- proper nutrition – vegetables and lean meat (preferably chicken, rabbit, beef) steamed should become the predominant part of the main diet;
- taking vitamin complexes, necessarily as prescribed by a doctor and under the supervision of laboratory tests of blood and urine;
- avoid colds, viral diseases and injuries;
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13-24 weeks
When calculating pregnancy by week, you need to keep in mind that from the 12th week, swelling and excess weight gain are very likely to occur due to the constantly growing appetite, so sticking to a diet will become a necessity.
- the diet should consist as much as possible of thermally unprocessed fruits and vegetables, include cottage cheese, preferably homemade;
- to avoid the formation of edema, avoid or minimize the intake of salty, spicy, fatty and smoked foods;
- Introduce fermented milk products and sauerkraut into your diet, but not in large quantities, so that there is no severe bloating. There is nothing scary about this, but the sensations will be unpleasant. The feeling of distension in the stomach is not entirely pleasant;
- don't forget to take vitamin complexes;
- protect your body from viruses, injuries and food poisoning.
25-36 weeks
It is still not advisable to make any concessions to the diet, you just need to dilute it with food that can have a laxative effect on the intestines and stick to the previously chosen daily routine:
- monitor your weight, do not gain excess weight, which will be a burden for the mother and will not benefit the baby;
- do not exceed the dosage of vitamins to avoid premature aging of the placenta;
- To avoid constipation, which often reoccurs in the later stages, it is advisable to eat dried apricots and prunes. The microelements contained in the named dried fruits will benefit not only the mother, but will also be useful for the baby.
Don't hold back your happiness
Waiting for a baby is an exciting and very responsible period. Some people approach it well prepared, while for others, the upcoming motherhood becomes a real surprise. In any case, the news that you will have a child is happiness. The feeling of joy, sublimity, should not leave a woman for a minute. Waiting, brightened by happy trepidation, will make the baby cheerful. Count your pregnancy by weeks, imagine each stage of the child's development, talk to him, tell him how happy you are that he is with you and everything will go easily, and the birth will pass without complications.