Calculation of pregnancy by week with description. Calculation of gestational age, methods for determining gestational age by week, calculator

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Express tour: pregnancy week by week

Pregnancy women lasts 280 days or 40 weeks, which is 9 months. This difficult path to meeting mother and baby is usually divided into trimesters, each a week which has its own characteristics and characteristics. Each trimester consists of three months.

First trimester: weeks 1-13

At the “start” after conception, an embryo is formed, but the signs are barely noticeable by the mother. Details:

• 1 Week— for pregnancy to occur, it is necessary to attach an egg traveling through the tubes to the wall of the uterus. The expectant mother feels the world more deeply and becomes more thoughtful. Many women at this stage feel symptoms like before menstruation - pulling in the lower back, aching in the stomach. To determine the length of pregnancy in weeks and calculate the date of delivery based on the last menstrual days, use our pregnancy calculator. Try not to take pills and eat right;
• 2 week- a follicle matures in the ovaries during ovulation, then it bursts, the egg comes out, the breasts become sensitive, irritability increases slightly, but libido also increases. No saunas or steam baths during this period! No heavy lifting! Only exercise, swimming, quitting smoking, orange juices and green vegetables, rich folic acid, helping to absorb iron! Taste habits change, you often want to go to the toilet, your blood pressure decreases;
• 3 week- the embryo lives in the mother’s body, the egg is fertilized by a sperm, divides, and after 2.5 weeks reaches the uterus, which by the end of this period becomes loose. Nothing prevents the egg from reliably attaching to the mucous membrane. The metabolism changes, the mammary glands become coarser. You need to replace sweets with nuts, eat foods rich in calcium, proteins, folic acid, iron;
• 4 week- the mother detects a delay in menstruation, nausea and malaise may appear. Hormones released during pregnancy can already be seen in the urine when laboratory analysis. The embryo develops internal organs, the mother needs vitamins;
• 5 week- the uterus thickens, the baby looks like a tadpole, but its eyes and nostrils are already formed, it already has a heart, and the base of the skeleton is formed. The baby receives nutrition and oxygen from the mother's blood. A woman’s ovaries actively release progesterone, and the mother’s immunity decreases. In 7 days, the embryo grows to half a centimeter;
• week 6— the amniotic sac is forming, protecting the embryo from any troubles, the nervous and circulatory systems are developing hourly. The processes of creation of the brain, liver, respiratory organs, and pancreas occur. The baby grows up to 1.3 cm;
• week 7— the size of the embryo’s head reaches 0.8 cm. The visual system is formed, the neural tubes thicken, top part the intestines are distinguished by the esophagus, stomach and pharynx, the bladder and rectum are visible under the lower one, and in male embryos - the prostate. A woman's facial skin may become oily during this period, like a teenager. Hormonal changes can cause itching. In case of any troubles, it is better to consult a doctor for advice;
• 8 week- receives maximum development nervous system, the medulla oblongata is ready for work, the spinal cord and brain have already fully formed, the eyes are still without eyelids, there is a nose, fingers and elbow joints appear on the arms. Mothers should protect themselves from infections;
• Week 9- the third month begins, the face takes on human features, eyelids form, a sucking reflex appears, the circulatory system circulates inside the tiny organism, the heart acquires three chambers, the bronchi branch. Mom's breasts increase so much that the next bra number is required. The uterus enlarges, the ligaments stretch, pulling sensations in the lower abdomen are normal for this period;
• 10 week— A 5-centimeter embryo is already considered a fetus; an ultrasound can determine its gender. His nervous system is divided into central and peripheral, the cerebral hemispheres become more independent. The enlarged uterus can be felt even with your hands, you constantly want to go to the toilet;
• 11 week- the baby’s body gradually straightens, reaching 5.9 cm, the legs begin to actively catch up with the arms, irises form near the eyes, and lymphocytes appear. The mother's kidneys experience a double load, removing waste products for two;
• 12 week- A 50-gram fetus has grown to more than 7 centimeters, the chest moves noticeably when breathing, the heart beats more than 150 beats per minute, milk teeth, vocal cords, and diaphragm are forming. The mother needs to get enough sleep, exercise, and remain calm;
• Week 13— the placenta has reached 16 mm, becoming reliable protection for the baby. From this point on, the body will even tolerate taking antibiotics if necessary. Bones and ribs need calcium. Without subcutaneous fatty tissue, the skin appears wrinkled. Mom may become constipated, her blood pressure may drop, and her kidneys may be bothered. It is important to eat right in order to gain no more than 11 kg during the entire pregnancy, and for a multiple pregnancy - no more than 17 kg;

Second trimester: 14-27 weeks

This is a gently flowing period of bearing a baby, during which the mother’s body is completely ready to work for two, despite the weight gain, rounding of shape, and the appearance of a belly. The embryo's internal organs and systems are fully formed, the child moves his limbs, sucks his finger, and the feeling of his movements gives the mother endless delight. More details:

• Week 14- the baby supports chemical composition amniotic fluid, releasing urine into it up to several times a day. The ovaries in girls and the prostate in boys are improving. Lack of vitamins affects the mother’s well-being. She has the feeling that there is not enough air. It is worth eating less potatoes and legumes. You may be allergic to strawberries, peaches, and oranges;
• Week 15- the baby’s heart distills about 23 liters of blood, convolutions form in the brain, bone marrow develops, the intestines form original feces, and the amount of amniotic fluid increases. You can talk to your baby! The height of the uterus reaches 14 cm. The woman begins to blossom;
• Week 16— the date the baby moves helps to more accurately determine the date of delivery; he actively moves every 10 minutes. He opens his eyes for the first time. Fetal movement may appear by the 20th week. Charging and correct menu improve the mother's condition;
• Week 17- the weight of the fetus exceeds 100 g, and the height reaches 12 cm. He and the mother require calcium and healthy food, since the body type is being determined. A woman feels pressure in her stomach and liver. You have to eat many times a day in small portions so that your stomach has time to cope. Sometimes leg cramps appear due to a lack of B vitamins, magnesium, calcium;
• Week 18- the height of a small child is 13 cm, weight - 170 g, head diameter - almost 4 cm, fingers become proportional, foot length reaches 2.5 cm. Mothers rejoice, feeling his movements. At this time, there is a high probability of determining the baby’s gender using an ultrasound. The ideal weekly weight gain for a mother is 500 g. To reduce swelling, you need to consume less salt;
• Week 19- the child reacts to screams, the volume of the voice, turns his head towards the sound. Listen to pleasant music, do not quarrel with your family. A pattern is formed on children's palms. The kicks in the tummy become more distinct. Women do not always distinguish the movement of the fetus from the processes that occur in the intestines;
• Week 20- the endocrine system is formed, parts of the brain are improving, the baby can swallow, has good hearing, his weight is about 290 g, his height is about 24 cm. Mommy’s waist disappears from the rounding of the tummy, the first stretch marks appear, a comfortable bra is required;
• 21 weeks- if a baby is suddenly born after this period, his ability to survive increases significantly. Systems and organs are formed, the stomach and chest, the head grow, subcutaneous fat is formed, receptors on the tongue distinguish taste, the first leukocytes appear in his body. Requires a lot of protein and 4 times more carbohydrates;
• Week 22- the brain weighs 100 g, the height of the fetus is 28 cm, weight is about 430 g, the mass of the heart increases, ligaments and vertebrae are clearly visible. It is necessary to count the child's movements, since swelling can transfer blood vessels, carrying nutrition to the placenta;
• Week 23- alveoli are formed, the respiratory system develops. Mom needs to drink a lot of water, since plasma consists of it. The fuzz on the child’s head is noticeable during ultrasound examination; the muscles, spine, bones, and aorta are clearly visible;
• Week 24— the baby’s skin gradually smoothes out, thanks to the appearance of subcutaneous fatty tissue. The baby feels the mother's emotions. The doctor listens to how the heart beats, whether the chest and tummy have grown, what is the diameter of the head;
• Week 25— the child’s weight is 680 g, height — 34 cm. Bone marrow connects to blood formation. In order for the alveoli to function, surfactant accumulates in the lungs. The fundus of the mother’s uterus has risen to 25 cm, her legs get tired more often, and lower back pain appears;
• Week 26— the baby has grown to 35 cm, gained more than 770 g, smells, reacts faster to voices. The diameter of the head is now 65.1 mm, the stomach is 67.4 mm, the chest is 65.8 mm. By this time, the woman puts things aside and spares herself more;
• Week 27- setting the speed of reactions and metabolic processes. The mother needs to gain strength for the upcoming third of gestation. The period is characterized by frequent shortness of breath due to a feeling of lack of air.

Third trimester: 28 weeks until delivery

The most difficult stage for a mother is from 7 months before giving birth. It is accompanied by the active growth of the baby, preparing the child for independent existence. Details:

• Week 28- the baby is exactly 7 months old, you can determine whether he will be right-handed or left-handed. To do this, the ultrasound shows which hand he most often reaches for his mouth. There is already enough surfactant in the lungs to prevent the alveoli from sticking together during the first breath;
• Week 29— the baby’s height has reached 38 cm, weight is more than 1 kg. Only his belly and folds are lubricated. He becomes cramped inside his mother, and the blood fully protects him from infections, but venous and arterial blood still mix. The daily portion of urine excreted is 500 g. The mother is entitled to maternity leave at this time;
• Week 30— the baby’s chest has grown to 77.4 mm, and the tummy has grown to 79.3 mm. The cerebral cortex is formed, the child begins to remember some sounds and sensations. Mom will have to visit the gynecologist weekly. Due to the increased pressure on the blood vessels during sleep, your arms go numb and your legs cramp. The ligaments become elastic, you can do light stretching exercises in the pelvic area;
• 31 weeks— the child’s weekly weight gain is about 200 g. The child needs subcutaneous fat that retains heat. The pigment accumulates in the hair and iris of the eyes. Sometimes the uterus rehearses childbirth, one-off contractions appear;
• Week 32- the baby weighs 1700 g, body length - over 40 cm. If the placenta “gets old”, nutrition will be disrupted, and developmental abnormalities will appear. By this period, the first hair appears. The mother produces vasopressin and oxytocin;
• Week 33- the child has to assume the fetal position because there is not enough space. The body reached 43 cm, the head - 8.2 cm, the tummy - 87.4 mm, the breast - 85 mm. The placenta copes with the function of protecting the baby from harmful factors and nourishes it through the blood;
• 34 week— the baby weighs 2.1 kg. The placenta produces hormones that cause lactation. Its thickness is 3.39 cm. It is important not to overdo it with calcium intake in order to avoid birth injuries. It is necessary to continue to count the movements of the fetus - 4-6 movements are considered the norm;
• — childbirth is possible this week, but much is determined by heredity. The head is 1/4 the length of the body, its diameter is 91 mm. The feet became more defined. The baby's genitals and reflexes are developed. The placenta dries out and supplies nutrition worse. The mother is focused on the upcoming meeting with the baby;
• Week 39- the baby weighs 3.3 kg, height - 51.5 cm. Thanks to the fontanelles made of cartilage tissue, the bones of the skull remain pliable so that the child can pass through the birth canal. The baby will be able to distinguish objects at a distance of 30 cm from the eyes. The placenta ages and the fetus experiences a lack of oxygen. Mom prepares things for the maternity hospital and documents;
• week 40- the child patiently waited for this hour, gained more than 3.5 kg, grew to 53 cm. The mother becomes worried if labor does not occur. Before giving birth, you often want to go to the toilet, your lower back ache, your cervix gradually opens, and colostrum is released from your nipples.

If labor does not occur at 40 weeks, it doesn’t matter. The norm is resolution within 42 weeks. All you have to do is trust nature. Only 10% of women in labor reach the 42nd week. Dopplerography and ultrasound are performed to assess the condition of the baby and mother. The main thing is to remain calm so as not to harm the health of mother and child.

"cervix" in Latin means "cervix") or the cervical canal. The cervix is ​​4 cm long and the width of the cervical canal is a maximum of 4 mm. The shape of the canal resembles a spindle, that is, its widest part is in the center of the cervix, and the canal narrows upward and downward. This form ensures the preservation of the mucous plug, which is normally present in the cervical canal.

Description

This calculator will allow you to calculate at what stage of pregnancy you are now, the date of future birth, the date of conception, and even the zodiac sign of the future baby and its zodiac animal. eastern calendar. You will also be able to determine the age of the fetus, its weight and height, and how much time is left before birth. To do this, you need to enter the date of the first day of your last menstruation and the duration of your menstrual cycle. In addition, our calculator generates a very convenient and practical pregnancy table by week. Using it, you can figure out what week of pregnancy you are currently in, as well as track the height and weight of your unborn child.

1-2 week

A new menstrual cycle begins in the first week, so at this time it is difficult to talk about actual pregnancy. However, obstetricians-gynecologists start counting not from the date of fertilization of the egg, but from the first day of the cycle. Ovulation occurs, then conception occurs, and only from the third week can we safely talk about pregnancy.

It's time to take care of your health, get rid of bad habits, switch to proper nutrition, and engage in light exercise (but only with your doctor's permission). These measures are very important for the health of the unborn baby, who in nine months will delight the world with his presence.

3-4 week

Child. The fertilized egg has already received all important information about the future person: color of eyes, hair, skin, gender. It now travels down the fallopian tube and into the uterus, where the embryo will develop. By the end of the fourth week it will reach a size of 1 mm.

Mother. A woman experiences the first signs of pregnancy: increased basal temperature, feeling tired, drowsiness, increased appetite, changes in taste preferences, nausea, intestinal upset, frequent urge to urination. Intolerance to hotel odors may occur. Bloody discharge is possible, but you should not be afraid of it. It's time to take a pregnancy test.

5-6 week

Child. At this time, the baby has already formed the main vital organs: heart, liver, kidneys, lungs. And at this time his heart begins to beat! You can hear the heartbeat on an ultrasound. Arms and legs begin to form. The length of the embryo reaches 4 mm, the volume of amniotic fluid is about 3 ml. Visual organs and cartilage tissue are formed. The placenta is actively growing.

Mother. During this period, a woman may experience increased nausea and irritability. The state of the body is similar to what happens before menstruation. It's time to visit a gynecologist who will prescribe the necessary tests.

7-8 week

Child. The umbilical cord is fully formed, ensuring blood circulation between the mother and child. Small hands and tiny fingers begin to form. At this time, the sex of the child is determined. The face, nose, nostrils, ears, and upper lip are formed. The epidermis is formed. The embryo slowly straightens, grows and reaches a weight of 4-6 g, length - 1.5-2 cm.

Mother. The uterus increases to the size of an orange, so the woman gradually develops a belly and feels tight in her clothes. You need to protect yourself from stress, heavy lifting, and sudden movements. On an ultrasound you can see the baby's first movements.

9-10 week

Child. The fetal head is still tilted forward and the chin is tucked toward the chest. The stomach begins to work, and it is already producing gastric juice. The baby develops facial expressions, eyelids form, but the eyes are still closed. The tail disappears completely. The embryonic stage ends and the baby is now called a fetus. The development of baby teeth begins. Now it weighs 7-8 g, length - 2.5-3 cm.

Mother. Mood swings become a common occurrence for women. The waist is rounded, 2-3 kg are added in weight. Hair becomes drier and skin becomes smoother. The work of the heart increases, because now it pumps about one and a half liters of blood per minute.

11-12 week

Child. The head still takes up half the size of the entire fetus as the brain grows rapidly. The kidneys begin to produce urine. The baby reaches a weight of about 13 g and already has real fingers and toes, and the rudiments of nails are developing. The length of the fetus is 4-5 cm. The formation of the iris of the eyes occurs. He begins to open his mouth. It's time to undergo the first ultrasound examination and get to know the child, and also rule out possible congenital anomalies.

Mother. By the end of the 12th week, a woman must register for pregnancy at the antenatal clinic and undergo appropriate examinations with a doctor. Taking vitamins for pregnant women is very important. And most importantly, at this time toxicosis completely passes.

13-14 week

Child. The baby develops a sucking reflex. He turns his head and moves his arms, somersaulting, although these movements are still invisible. You can often see him sucking his thumb on ultrasound! The child grows and his weight becomes about 43 g, and his length is 6-8 cm. The genitals acquire clear outlines. The embryonic fluff appears - lanugo.

Mother. Finally, the tummy becomes noticeable; a longitudinal brown stripe appears on it. Freckles and age spots appear. Constipation may occur. The uterus rises from the pelvis into the abdominal cavity, and the pregnant woman’s appetite increases significantly.

15-16 week

Child. Hairs begin to grow on the baby's head. It actively swims in the amniotic fluid, which tends to renew itself every 3 hours. The baby produces urine every 45 minutes. At week 16, there is a chance to feel the baby's first movements! The facial muscles have already formed. Marigolds begin to appear and the grasping reflex appears. Weight – about 100 g, length – 12 cm.

Mother. It is worth taking care of your body and purchasing oil against stretch marks. It is very important to visit the dentist, because your body is now actively releasing calcium to your baby, so teeth can deteriorate. It's also time to buy special maternity clothes.

17-18 week

Child. The baby's weight is 140-190 g, length is 14 cm. Most of the bones have already been formed and continue to strengthen. The baby may swallow amniotic fluid. He can already hear well, so you need to talk to him more often and play soft music. During this period, you will definitely feel the baby’s movements, which cannot be confused with anything.

Mother. The woman's breasts become enlarged and colostrum can be produced. The expectant mother may suffer from constipation, so you need to eat more fruits and fresh vegetables. Urination becomes more frequent as the uterus puts a lot of pressure on the bladder.

19-20 week

Child. The baby's body is covered with primordial fluff, his arms are stretched out, he turns his head in different directions. The placenta moves deep into the uterus. The rudiments of permanent teeth appear. The baby's growth slows down, and subcutaneous fat now appears. A birth lubricant is formed covering the folds of the skin. The baby turns towards the light. A second ultrasound examination is carried out to accurately determine the sex of the unborn baby. Its weight is about 300 g, length is 16 cm.

Mother. The back receives a significant load, so you should ensure correct posture and wear comfortable shoes without heels. Brown or red stripes (stretch marks) may appear on the abdomen, thighs and chest.

21-22 weeks

Child. The baby learns to bend and straighten his arms, legs, and grab his heels. Pads with nerve endings appear on the fingers. Eyebrows are indicated on the face. The amount of blood in the body increases. The liquid it captures turns into a solid. It will remain in the intestines until delivery. The baby's weight is 360-430 g, length - 28 cm.

Mother. The first half of the pregnancy was successful. The uterus changes its shape and stretches. Lying on your back is harmful for the baby; he may suffer from a lack of oxygen. Libido increases. Since the fetus is reliably protected, sex cannot harm the child.

23-24 week

Child. The baby's weight reaches 500-600 g, length - 30 cm. Most He sleeps for a while, taking short breaks to stay awake. The skin is a little saggy, as the fat layer has just begun to grow. It pushes with its legs from the inside, floating in the amniotic fluid. Eyelashes appear on the eyelids. The respiratory system develops. Also, the baby is becoming more and more sensitive to the world around him.

Mother. At this time, a woman may experience training contractions, which manifest themselves in the form of short-term painless contractions. Weight gain increases rapidly and reaches 5 kg! Possible heaviness in the legs.

25-26 week

Child. The formation of neurons around the neural tube is completed. The baby is active until late in the evening and sleeps soundly in the morning. He clenches his fists, and at this time it is determined whether he will be left-handed or right-handed. The fetal heartbeat can be heard even without special devices. The lungs are fully formed. 20 rudiments of baby teeth are formed in the jaws, and under them - 20 rudiments of permanent teeth. The remaining 12 are formed after birth. Weight is 660-800 g, length – 35 cm.

Mother. The uterus has enlarged and puts pressure on the diaphragm, displacing the stomach from the abdominal cavity. Because of this, gastric juice rises into the esophagus and heartburn occurs.

27-28 week

Child. The baby's skin is becoming more and more wrinkled. The movements become more and more strong. If the baby is born at this time, his chance of survival is 85%. The child tries to breathe on his own, developing his lungs. He still has enough room to turn himself into the correct position - head down. Weight – 900-1100 g, length – 37 cm.

Mother. Female shapes become more rounded, and blood cholesterol levels increase. While sitting, the uterus puts pressure on the vena cava, which leads to a lack of oxygen and dizziness. Training contractions of the uterus become more frequent. It is worth finding time for proper rest.

29-30 week

Child. The baby's nostrils are free of mucus plugs and amniotic fluid enters them. He already knows how to open and close his eyes and reacts to bright light. The immune system begins its work. The child produces about 500 ml of urine per day. On ultrasound, movements of the chest are noticeable. Enamel appears on the teeth. The baby's weight reaches 1300 g, length - 39 cm.

Mother. The kidneys work harder and may not be able to cope with the amount of fluid entering them, which can lead to the formation of edema. The organs near the uterus are becoming increasingly crowded. The weight of the expectant mother is actively increasing, movements become more clumsy and relatively slow.

31-32 weeks

Child. The baby becomes plump, thus preparing a protective layer against temperature changes in the future. In boys, the testicles descend into the scrotum and reach their extreme position. The child reacts to strong sounds from the outside, despite the fact that the amniotic fluid creates a kind of plug in the ears. The kidneys are already working well. The nail plate reaches the fingertips. Weight 1600-1900 g, length – 42 cm.

Mother. A woman may experience swelling and dilation of the veins in her legs, so she needs to control her fluid intake and take walks at fresh air. At this time, a Doppler ultrasound examination of the baby’s circulatory system is performed.

33-34 weeks

Child. The baby becomes cramped in the womb, so he moves less often than before. The child continues to consume calcium from the mother’s body, which is so important for the formation of the skeleton. A skin pattern appears on the fingers and toes. The skin is now less red, and the hair on the head becomes thicker. Baby weight – 1900-2400 g, length – 45 cm.

Mother. The woman begins to feel short of breath because the two have to consume more oxygen. The gums become soft, bleeding and gingivitis may occur. Forgetfulness and absent-mindedness appear. You should remain calm in any case, because the baby subtly feels the mother’s worries.

35-36 week

Child. In the last weeks of life, the baby's fluff begins to disappear in the womb. The skin becomes pink color and is smoothed out thanks to subcutaneous fat. The cheeks become plumper, this will help in the future to receive food in the right quantity. The amniotic fluid takes on a sticky and viscous consistency. Internal organs continue to improve. The baby's weight is 2400-2600 g, length - 47 cm.

Mother. To reduce sleep problems, it is advisable to drink less fluid at night. If heartburn occurs, you need to eat small portions, but often. Time suitable for attending courses for pregnant women, choosing a maternity hospital, choosing an obstetrician.

37-38 week

Child. The baby has already turned his head down. It loses its original fluff and there is much less lubrication. Sometimes he scratches himself, making awkward movements with his arms. His lungs are ready to breathe air. The expectant mother may feel her baby hiccupping in her tummy. Its weight is 3000 g, length - 50 cm.

Mother. The pregnant woman's belly has dropped, and now breathing has become much easier. The uterus has increased as much as possible, its volume is 4-5 liters. The pregnancy can already be considered fully term. Now labor can begin any day now, so things for the maternity hospital should be collected in bags.

39-40 week

Child. Most newborns are born with long nails, because by this time they have fully grown. The child’s activity slows down, because his tummy has long been cramped and dark. His intestines are filled with original feces - meconium, which will come out, most likely, after birth. The length of the hair on the head is about 2 cm. The average weight of a child is 3200-3500 g, length - 52 cm. The baby is completely ready for birth - meet the main person in your life!

Mother. A woman suffers from insomnia and has pain in her lower back. The cervix begins to shorten and dilate. The uterus puts more pressure on the bladder. False or real contractions may appear. Childbirth occurs with an error of 1-2 weeks earlier or later than a certain date.

41-42 weeks

Child. The baby is fully developed, all his organs are functioning correctly. He continues to grow and gain weight; his tummy has become very cramped. The bones of the skull continue to strengthen, which may make it a little more difficult for the baby to pass through the birth canal. You need to count the number of movements per hour, and if it is at least 10, everything is fine with the baby.

Mother. Until the end of the 42nd week, pregnancy is not considered post-term. If the baby has not been born by this time, there is still no cause for concern. Labor can be stimulated by long walks, bending forward, and sex with your husband. If you have not given birth by this time, practice breathing techniques, give valuable instructions to relatives - and quickly go to the delivery room!

Update: October 2018

Any woman preparing to become a mother eagerly awaits the appearance of the two coveted lines on the test. After this moment, worries and worries arise. Is the baby developing normally, when should you go for the first ultrasound, and, finally, when is the birth expected? All these questions can be answered by knowing the exact duration of pregnancy.

What is the gestational age?

Very often, confusion in a pregnant woman’s head arises due to a misunderstanding of this term. Therefore, it is important to know when embryo development begins and when the countdown to birth begins.

After ovulation (release from the ovary), the egg lives for about a day. This is the time that is considered the most favorable for conception. With a menstrual cycle of 28 days, ovulation occurs on the 14th day. At the moment of fertilization, the sperm fuses with the egg, and after a week the developing embryo attaches to the inner lining of the uterus.

Since most women have variable menstrual cycle length, no one knows the exact date of ovulation and conception. Therefore, all obstetricians in the world consider the first day of the last menstruation to be the beginning of pregnancy. 9 months (280 days) after this day the birth should take place. This is the paradox: the pregnancy countdown has already begun, but conception has not yet occurred. Therefore, the lifespan of an embryo is less than the gestation period by an average of 2 weeks.

Methods for determining gestational age and due date

All doctors in the world determine the duration of pregnancy using one main parameter (ultrasound) and two auxiliary parameters (date of menstruation and examination of the pregnant woman).

Ultrasound

The main method is ultrasound examination. It is important to remember that the accuracy of this method is maximum in the first 10-12 weeks, and then it decreases. Therefore, ultrasound of the first trimester is widely used to determine the expected date of birth.

Modern devices can detect the fertilized egg in the uterus as early as 3-5 weeks of pregnancy. As the embryo grows to 3-4 mm, it becomes possible to measure its CTE (coccygeal-parietal size), which serves as the basis for determining the gestational age accurate to the day. Usually, in the conclusion, the doctor indicates which period he has in mind: obstetric (from the last menstruation) or embryonic (from the moment of conception).

After 22 weeks of pregnancy, it is impossible to accurately determine the age of the fetus. But measuring its main parameters (size of the head, length of the femur, abdominal circumference) allows us to assess the dynamics of growth. If it does not correspond to the period stated during ultrasound in the 1st trimester, then there is a possibility of fetal growth retardation syndrome. In addition, there are individual hereditary characteristics (short stature, large head), due to which in the third trimester the gestational age cannot be calculated by ultrasound.

Date of last menstruation - calculation calculator

Determining the gestational age by the day of the last menstruation is the most accessible way for a woman. If future mom If she is a happy owner of a regular cycle of 28 days, then she can independently and quite accurately calculate the date of birth. There are special Naegele formulas for this.

PDR = PDPM - 3 months + 7 days

• EDA – estimated date of birth
• PDPM – first day of last menstruation

For example, if the PDPM was on June 15, then the PDP = June 15 - 3 months + 7 days = March 15 + 7 days = March 21. This is the basis for determining the date of birth in all special calculators for calculating the duration of pregnancy.

The gestational age is determined by adding the number of weeks that have passed since this day to the PDPM. Therefore, every woman can calculate the duration of pregnancy using a regular calendar.

When is it impossible to determine the period of menstruation?

• Irregular menstrual cycle. With a cycle longer than 35 days, ovulation does not occur on the 14th day. Therefore, Nägele’s formula will give an inaccurate result (see).
• Taking contraceptives. If you do not take oral contraceptives regularly, pregnancy may occur. Due to sudden ovulation, the formula for calculating the PDP is also not suitable (see).
• If there is a threat of miscarriage early dates . It happens that there is a threat of termination of pregnancy at the earliest possible stage. Very often it manifests itself as scanty bleeding on the days corresponding to the expected menstruation. That is, a woman can confuse bleeding at the 5th week of pregnancy and normal periods, and will not even guess about her interesting position. In such cases, the period is determined using ultrasound.

Examination of a pregnant woman

Registration of every pregnant woman with antenatal clinic starts with an inspection. Determining the size of the uterus and the height of its fundus (that is, the upper part) can provide approximate information about the gestational age. This method is not 100% accurate. After all, the individual location of the uterus, fibroids and a full bladder can make examination difficult. And multiple pregnancy is associated with a large increase in this organ.

HCG level

Already 8-10 days after conception, the B-subunit of hCG is detected in the blood of the expectant mother. This hormone appears during pregnancy and doubles every 2-3 days (see). It is possible to judge the gestational age by its level only indirectly.

• Firstly, hCG norms for each week of pregnancy have a wide range.
• Secondly, its level increases with multiple pregnancies and some fetal anomalies. Therefore, there is no point in relying on this hormone when calculating the gestational age by week, when more accurate methods are available (ultrasound, for example).

Date of first movement

It is believed that primiparous women feel fetal movements from the 20th week of pregnancy. Multiparous women can feel them as early as 16-18 weeks. In fact, it all depends on the individual characteristics of the mother and child, the thickness of the fat layer on the pregnant woman’s abdomen and her desire to feel the kicks. In addition, intestinal peristalsis is often mistaken for the first movements. Therefore, you should not rely on this indicator in calculating the gestational age.

How to determine the gestational age during IVF?

During in vitro fertilization, many women doubt how to correctly count the weeks of pregnancy. After all, an already developing embryo is implanted into the uterine cavity. But regardless of the method of fertilization (naturally, sperm insemination or IVF), the gestational age is determined from the first day of the last menstruation. The only exception can be considered IVF with a protocol for suppressing menstruation (superlong protocol). In this case, the period is counted from the day of embryo transfer with the addition of two weeks.

Why do doctors determine the exact duration of pregnancy?

• To assess the rate of fetal development
• To determine the due date
• To screen for chromosomal mutations (Down syndrome, etc.)
• To determine the viability of a child during premature birth

The main goal of determining the gestational age for the expectant mother is to tune in to the approaching birth of the baby and get acquainted with information about intrauterine development week by week.

Calculating the gestational age with an accuracy of one day is very difficult and is possible, perhaps, only if ovulation is specifically monitored using ultrasound. But these procedures are carried out only for the treatment of infertility. Therefore, the day of conception often remains a secret even for the couple themselves, not to mention the doctors.

And yet, are there any calendar methods for calculating conception? Is it possible to calculate the gestational age based on the menstrual cycle and the day of delay? What procedures and tests help in diagnosis and calculations? You will read about all this in the article.

Calendar methods

If sexual intercourse does not occur too often, then it is quite possible that a woman will remember exactly on what day that same nimble sperm entered her body, which subsequently fertilized the egg. This is also possible if a woman carefully measures her basal temperature over several cycles and knows how to use the resulting graphs with temperature values. She tells the doctor this calculated day after her pregnancy is confirmed. However, the doctor, having found out when the patient’s last period was, calls the period 2 weeks longer. How can this be and what to believe?

The fact is that doctors calculate the obstetric period, and it depends only on the first day of the last menstruation. It turns out that pregnancy begins on the first day of menstruation, although this is not true, of course. But this calculation method turns out to be quite accurate. And using the same method, the expected date of birth is calculated: 280 days are added to the first day of the last menstruation, or 3 months are subtracted and 7 days are added (according to Naegele’s formula).

If the day of ovulation is known exactly, then we can add not 280 days to the first day of the menstrual cycle, but 264. And in this way we will also find out the estimated due date. Well, you can start counting pregnancy from the day of ovulation. But again, doctors do not conduct such calculations, and these values ​​are not taken into account.

Ultrasonography

Ultrasound has been actively used for many years to diagnose fetal development. And with the help of ultrasound, the gestational age is determined. Particularly accurate in this regard are studies conducted in the first weeks of pregnancy (up to 8 weeks). During this period, all healthy embryos develop equally, and the gestational age according to the size of the fetus is determined exactly down to the day. How longer term- the more mistakes there are, since children begin to show individuality in a sense - one may have a slightly larger head than it should be at a certain time, while another baby has a height slightly below his age limits. If the deviations are minor - a week or less - then doctors, as a rule, do not take them into account, and nothing needs to be treated. The estimated period is set based on measurement data of the coccygeal-parietal size. The result is obtained using a table.

If there is a developmental delay of 2 weeks or more, despite all this, there is confidence that there is no error in setting the gestational age, the doctor makes a diagnosis of “intrauterine growth retardation.” It is impossible to “cure” her. Everything that is done in the hospital has only a preventive, and not too pronounced, effect. Good food healthy image life, walks, quiet leisure - that’s what’s much more important.

Gynecological examination

Many women go to the gynecologist on the first day of the delay, or even earlier, in the hope that the doctor will be able to tell for sure whether they are pregnant or not. But this is impossible, unfortunately. The uterus may be slightly enlarged before menstruation. The growth of the uterus, due to the development of the fetus in it, begins noticeably from the end of the first trimester. At 5-6 weeks (that is, in the second or third week of delayed menstruation), the uterus slightly exceeds its normal size, the volume can be compared with chicken egg. At 8 weeks the uterus is already the size of a goose egg, and at 10 weeks it is the size of a woman’s fist. Again, gynecological examinations are more accurate in determining the duration of pregnancy, the shorter it is.

Date of first movement

All gynecologists inspire their patients, expectant mothers, that they must remember the day when they first felt the baby inside them, that is, they felt his movements. It is believed that in pregnant women for the first time this occurs at exactly 20 weeks of pregnancy, and in pregnant women again - at exactly 18 weeks. This date must be included in the pregnant woman’s dispensary card and taken into account when determining the expected date of birth. Although, if you believe the statements of many expectant mothers, the timing of the first movements does not always coincide with the “book” ones. I would also like to reassure a little hyper-responsible expectant mothers who are afraid that they will not notice the first movements, thereby confusing the doctor when setting the date of birth, which can lead to post-term pregnancy. Firstly, postmaturity is diagnosed based on the results of Doppler ultrasound and some ultrasound indicators (maturity of the placenta, volume of amniotic fluid, etc.). And secondly, the first movements are indeed very light, but quite noticeable. It is impossible not to notice movement if you are in a horizontal position, especially on your back.

Uterus length

From approximately the second trimester of pregnancy, and sometimes earlier, gynecologists evaluate fetal development based on the length of the uterus. It is measured with a measuring tape, the expectant mother lies on the couch. Every week it adds about 1 centimeter. There is another measurement method; many doctors use the corresponding tablets, and they can also be found in manuals on obstetrics and gynecology.

12 weeks - uterus at the upper edge of the womb

14 weeks - the uterus is two fingers higher than the womb

16 weeks - the fundus of the uterus is felt between the navel and womb

20 weeks - the fundus of the uterus is two fingers below the navel

24 weeks - uterus at navel level

28 weeks - the fundus of the uterus is 2 fingers above the navel

32 weeks - between the navel and the xiphoid process (the shortest part of the sternum), length 28-30 cm

36 weeks - the fundus of the uterus is at the level of the xiphoid process, “supports” the ribs, length 32-34 cm

40 weeks - before birth, the uterus drops to the level of 32 weeks, as the baby’s head (or other presenting part of the fetus) moves lower into the pelvis and prepares for release.

In addition to the length of the uterus, the volume of the abdomen is also taken into account, but these dimensions are more variable, do not always show the true state of affairs and help calculate the gestational age by week. Abdominal volume is measured at the level of the navel. So, in a woman with normal weight before and during pregnancy, the abdominal volume at 32 weeks will be approximately 85 centimeters, and by the end of pregnancy it will reach 90-100 cm. This increase is associated with the rapid weight gain of the child.

The length of the uterus not only helps to verify the normal development of the fetus and the gestational age, but also to detect in time such pathologies as polyhydramnios or oligohydramnios and others.

Heart sounds

The baby’s heart begins to beat already at 4.5 weeks, that is, 2-3 weeks after the start of a woman’s delayed menstruation. Heartbeats are visible on ultrasound, and this is the main sign that the embryo is alive and developing. Later, the doctor begins to hear the heartbeat through the outer wall of the uterus. But you can only hear heart sounds not at 10-12 weeks, but later - at about the same time as you feel the first movements. The heartbeat is heard using an obstetric stethoscope - a special tube that the doctor places on the patient’s stomach. The heartbeat can be heard poorly for several reasons. The most “harmless” of them are the placenta, which is located on the anterior wall of the uterus, and thereby muffles the sound, and significant deposits of fat on the abdominal wall. More serious - polyhydramnios, chronic hypoxia. The longer the period, the more clearly the heart rhythms can be heard.

Human chorionic gonadotropin level

This method of determining the duration of pregnancy is usually used in the first weeks. But it does not always give an accurate result. A blood test is taken from a vein.

Approximate hCG values ​​for the first weeks of pregnancy:

• 2 - 25-300 honey/ml
• 3- 1500-5000 mU/ml
• 4 - 10000 - 30000 mU/ml
• 5 - 20000 - 100000 mU/ml

As you can see, the values ​​can vary greatly, so errors in the calculations are possible. This analysis is ideally used not for calculating timing, but for early diagnosis of pregnancy and its possible pathologies.

We have given the main ways to correctly calculate the duration of pregnancy. Some of them you can try on your own, others require medical intervention and some procedures.

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Pregnancy calendar: waiting for a miracle

Pregnancy in the life of every woman is forty weeks of pleasant troubles, unforgettable sensations and, of course, many questions. What happens to the baby before he is born? How should a future mother behave correctly in a given situation? You will find all the answers to the problems that concern you in our pregnancy calendar.

What will you see

In our calendar you will find forty chapters - one for each week of pregnancy. Each chapter is a 7-day story of the baby's life inside your tummy, written in understandable human language. But that is not all! All chapters are supplemented with many illustrations, photographs of expectant mothers and charming bellies, and ultrasound images.

What you will learn about

Note for pregnant women

Our calendar is a unique combination useful tips and recommendations from doctors, psychologists, lawyers, and site visitors. You will find interesting illustrations and beautiful pictures. And, of course, the impressions of expectant mothers every week of pregnancy.