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How many weeks does third trimester start
28 Weeks Pregnant | Pregnancy
Welcome to the 3rd trimester! Pregnancy is divided into 3 stages, known as trimesters…. and you're now in the 3rd stage. Over the next few weeks, you will probably start to feel a bit more uncomfortable and tired.
What's happening in my body?
You may be getting a bit of heartburn and indigestion. That's down to your growing baby and hormones affecting your digestive system.
Your back will also be under strain, due to the extra weight you're carrying around. Your joints and ligaments will also be looser than usual.
Your ankles, feet and face could be puffing out a bit, particularly when it's hot. This is probably due to water retention, but get it checked out, just in case it's pre-eclampsia. This is a condition where you may feel perfectly well, but then your blood pressure can get dangerously high, very quickly.
Rest can help with a lot of your symptoms, so make sure you get lots of it. But if you are worried about anything at all, talk to your midwife or doctor, or call NHS 111.
3 ways to bust germs
Make sure you know about some of the harmful infections in pregnancy, so that you can do your best to avoid them.
Here are 3 ways you can protect your unborn baby…
Wash your hands regularly with soap and water for at least 20 seconds, particularly if you're in contact with children or nappies, as they could carry a virus called CMV (cytomegalovirus).
If you have a cat - wear gloves when emptying the cat litter tray, or ask someone else to deal with it. That's because cat poo can contain a bug that causes the dangerous toxoplasmosis infection. You should also wear gloves when gardening, in case you come into contact with animal poo.
If you have not had chickenpox let your doctor or midwife know if you come into contact with anyone who could be infectious. The disease can be spread up to 2 days before spots appear, until 5 days afterwards. It's safest for you when there are no new blisters or moist crusts on the spots.
If you're worried about coronavirus, have a look at the guidance from Royal College of Obstetricians and Gynaecologists on coronavirus and pregnancy.
Nosebleeds are common in pregnancy, due to hormonal changes, and can even strike when you're asleep. Here's what you can do:
sit or stand up - don't lie down
pinch your nose just above your nostrils for 10 to 15 minutes
lean forward and breathe through your mouth
put an icepack (or a bag of frozen peas wrapped in a tea towel) at the top of your nose
Read more tips for stopping nosebleeds.
3rd trimester pregnancy symptoms (at 28 weeks)
You may start getting new symptoms now, such as nosebleeds and indigestion.
Your signs of pregnancy could also include:
sleeping problems (week 19 has information about feeling tired)
stretch marks (read about stretch marks on week 17's page)
swollen and bleeding gums (week 13 has information about gum health during pregnancy)
pains on the side of your baby bump, caused by your expanding womb ("round ligament pains")
piles (read about piles on week 22's page)
indigestion and heartburn (week 25 talks about digestive problems)
bloating and constipation (read about bloating on week 16's page)
leg cramps (week 20 explains how to deal with cramp)
swollen hands and feet
vaginal infections (see week 15 for vaginal health)
darkened skin on your face or brown patches – this is known as chloasma or the "mask of pregnancy"
greasier, spotty skin
thicker and shinier hair
You may also experience symptoms from earlier weeks, such as:
mood swings (week 8's page has information on mood swings)
morning sickness (read about dealing with morning sickness on week 6's page)
weird pregnancy cravings (read about pregnancy cravings on week 5's page)
a heightened sense of smell
sore or leaky breasts (read about breast pain on week 14's page) - a white milky pregnancy discharge from your vagina and light spotting (seek medical advice for any bleeding)
Read Tommy's guide to common pregnancy symptoms.
What does my baby look like?
Your baby, or foetus, is around 37.6cm long from head to heel, and weighs about 1kg. That's approximately the size of a pineapple, and the weight of a big bag of brown sugar.
Your baby's heart rate is changing all the time. Around week 5 or 6, when it was first detectable, it was around 110 beats per minute (bpm). Then it soared to around 170 bpm in week 9 and 10. Now, it's slowed down to around 140 bpm and it will be around 130 bpm at birth.
That's still a lot faster than your heart rate, which will be around 80 to 85 beats per minute. This is partly because babies' hearts are so small that they can't pump much blood, but they can make up for this by going faster. It also helps to keep them warm.
Your baby's heart can be heard through a stethoscope. Someone else might be able to hear it by putting an ear to your pregnant belly – give it a go, but it's tricky finding the right spot.
It's time to work out where your baby will sleep, and it's best to do this sooner, rather than later, before you start running out of energy. Your baby will spend a lot of time in a cot, so make sure it's safe. If you're buying a new cot, look for the British Standard mark BS EN 716-1. Read more about what you need for your baby.
This week you could also...
You have maternity rights. You can ask for a risk assessment of your work place to ensure that you're working in a safe environment. You should not be lifting heavy things and you may need extra breaks and somewhere to sit. You can also attend antenatal appointments during paid work time.
It's a good time to tone up your pelvic floor muscles. Gentle exercises can help to prevent leakage when you laugh, sneeze or cough. Get the muscles going by pretending that you're having a wee and then stopping midflow. Visit Tommy’s for more ideas about pelvic floor exercises.
Ask your midwife or doctor about online antenatal classes – they start around now. The charity Tommy's has lots of useful information on antenatal classes and preparing you for birth.
Even if you've had children before, they're still worth going to as you can meet other parents-to-be. The NCT offers online antenatal classes with small groups of people that live locally to you.
To keep bones and muscles healthy, we need vitamin D. From late March/early April to the end of September, most people make enough vitamin D from sunlight on their skin. However, between October and early March, you should consider taking a daily vitamin D supplement because we cannot make enough from sunlight.
Some people should take a vitamin D supplement all year round, find out if this applies to you on the NHS website. You just need 10 micrograms (it's the same for grown-ups and kids). Check if you're entitled to free vitamins.
It's recommended that you do 150 minutes of exercise a week while pregnant. You could start off with just 10 minutes of daily exercise - perhaps take a brisk walk outside. Check out Sport England's #StayInWorkOut online exercises (scroll to the pregnancy section). Listen to your body and do what feels right for you.
There's no need to eat for 2. Now you're in the 3rd trimester, you may need an extra 200 calories a day, but that's not much. It's about the same as 2 slices of wholemeal toast and margarine.
Try and eat healthily with plenty of fresh fruit and veg, and avoid processed, fatty and salty foods. You may be able to get free milk, fruit and veg through the Healthy Start scheme.
How are you today? If you're feeling anxious or low, then talk to your midwife or doctor who can point you in the right direction to get all the support that you need. You could also discuss your worries with your partner, friends and family.
You may be worried about your relationship, or money, or having somewhere permanent to live. Don't keep it to yourself. It's important that you ask for help if you need it.
Getting pregnant again is probably the last thing on your mind. However now is a good time to start planning what type of contraception you would like to use after your baby is born. Getting pregnant again could happen sooner than you realise and too short a gap between babies is known to cause problems. Talk to your GP or midwife to help you decide.
You will be offered newborn screening tests for your baby soon after they are born. These screening tests are recommended by the NHS. This is because these tests can make sure that your baby is given appropriate treatment as quickly as possible. Your decisions about whether or not you want this tests will be respected, and health care professionals will support you. Ask your midwife or doctor for more information about newborn screening.
You and your family should follow the government and NHS guidance on coronavirus (COVID-19):
read government guidance on how to stay safe from COVID-19
get NHS advice about COVID-19
use the NHS COVID-19 app for England and Wales – it's the fastest way of knowing when you've been exposed to COVID-19
To find out about about COVID-19 and pregnancy, childbirth and breastfeeding, have a look at advice on the:
World Health Organization
Third Trimester of Pregnancy: Fetal Development
The third trimester of pregnancy starts in week 28 of your pregnancy and lasts until you give birth, which is around the 40th week. The third trimester can be tiring and more uncomfortable as your baby takes up more room and you experience: Backaches: Pregnancy hormones relax the connective tissue that holds your bones in place, especially in the pelvic area. These changes can cause backaches and other discomfort during the third trimester. When you sit, choose chairs with good back support. Get regular exercise. Wear flat or low-heeled shoes with good arch support. Our sponsor, Slumbar has a great pregnancy pillow to help you sleep, sit and be more comfortable. Shortness of breath: You might get winded easily. Good posture will give your lungs more room to expand. Heartburn. Pregnancy hormones relaxing the valve between your stomach and esophagus can allow stomach acid to reflux into your esophagus, causing heartburn. To prevent heartburn, eat small, frequent meals and avoid fried foods, citrus fruits, chocolate, and spicy or fried foods. Our sponsor Nightfood’s Nighttime Ice Cream is specially formulated to be easier to digest and uses not artificial sweeteners or erythritol, and contains ingredients that research indicates are effective against heartburn. Spider veins, varicose veins and hemorrhoids: Increased blood circulation might cause tiny red-purplish veins (spider veins) to appear on your face, neck and arms. You might also experience swollen veins (varicose veins) on your legs, and hemorrhoids. To ease swelling, exercise and elevate your legs frequently, include plenty of fiber in your diet and drink lots of fluids. For hemorrhoid relief, soak in a warm tub or apply witch hazel pads to the area. Frequent urination. As your baby moves deeper into your pelvis, you’ll feel more pressure on your bladder and the need to urinate more often. This extra pressure might also cause you to leak urine when you laugh, cough, sneeze, bend or lift. If this is a problem, consider using panty liners.
How Your Baby is Developing Now:
Weeks 27 thru 32 – Gestational Age (Fetal Age – Weeks 25 thru 30)
The fetus really fills out over these next few weeks, storing fat on the body, reaching about 15-17 inches long and weighing about 4-4 ½ lbs by the 32nd week. The lungs are not fully mature yet, but some rhythmic breathing movements are occurring. The bones are fully developed but are still soft and pliable. The fetus is storing its own calcium, iron, and phosphorus. The eyelids open after being closed, since the end of the first trimester.
Weeks 33 thru 36 – Gestational Age (Fetal Age – Weeks 31 thru 34)
This is about the time that the fetus will descend into the head-down position preparing for birth. The fetus is beginning to gain weight more rapidly. The lanugo hair will disappear from the skin, and it is becoming less red and wrinkled. The fetus is now 16-19 inches and weighs anywhere from 5 ¾ lbs to 6 ¾ lbs.
Weeks 37 thru 40 – Gestational Age (Fetal Age – Weeks 35 thru 38)
At 38 weeks the fetus is considered full-term and is ready to make its appearance at any time. As your baby becomes bigger, you may notice a change in fetal movement. If you notice a decrease in fetal movement, make sure to talk with your doctor. The fingernails have grown long and will need to be cut soon after birth. Small breast buds are present on both sexes. The mother is supplying the fetus with antibodies that will help protect against disease. All organs are developed, with the lungs maturing all the way until the day of delivery. The fetus is about 19 – 21 inches in length and weighs anywhere from 6 ¾ lbs to 10 lbs.
Want to Know More?
16 Ways to Bond WIth Your Baby While Pregnant
Nutrients and Vitamins for Pregnancy
Creating Your Birth Plan
Signs of Labor
You are pregnant! Your baby will be born in 40 weeks. What changes will occur in your body, how your baby will grow will tell "Calendar of pregnancy".
Pregnancy begins at the moment of fertilization or conception.
Fertilization is a complex biological process of the fusion of female and male germ cells (egg and sperm). The resulting cell (zygote) is a new daughter organism.
A mature egg leaves the ovary approximately on the 12-14th day of the menstrual cycle (ovulation) and enters the fallopian tube, where it remains viable for 24 hours. During an orgasm, a man ejects from 200 to 400 million spermatozoa into the woman's vagina. Some of them penetrate through the cervix into the uterine cavity, and from there into the fallopian tubes. Here, spermatozoa retain the ability to fertilize for 48 hours. Thus, within 6-7 days of a woman's menstrual cycle, conception is possible.
Fertilization of the female egg is performed by a single sperm in the upper part of the fallopian tube. There are two types of sperm: those containing the Y chromosome (“male”) and the X chromosome (“female”). When an egg cell (containing the X chromosome) fuses with a sperm cell, their genetic material is combined and the sex of the child is determined. If there are two X chromosomes in the child's genetic makeup, it's a girl; if an X chromosome and a Y chromosome, it's a boy. It is impossible to change the sex of the child, so you should not follow the "folk beliefs" that guarantee the birth of a child of a given gender.
The fertilized egg begins to divide with the formation of a multicellular organism and move through the fallopian tube into the uterine cavity. During this period, the nutrition of the embryo is carried out at the expense of those substances that have been accumulated in the egg. If the peristalsis of the tube is slowed down (due to inflammatory diseases), the embryo penetrates the wall of the fallopian tube with the occurrence of an ectopic pregnancy.
Implantation (introduction) of the embryo into the uterine wall occurs 7-8 days after fertilization.
On the seventh day of pregnancy, the outer layer of the embryo (trophoblast) begins to produce a hormone - chorionic gonadotropin. This hormone gives the mother's body information that pregnancy has occurred, and begins its functional restructuring. Diagnostic test strips detect the chorionic gonadotropin in the urine of a pregnant woman, which makes it possible to diagnose pregnancy at an early stage.
You do not have the expected menstruation, nausea in the morning, and frequent urination during the day. You become emotionally labile, irritable, whiny. Basal body temperature is above 37°C. In appearance, your unborn baby resembles a small auricle measuring 4 mm, surrounded by a small amount of amniotic fluid. On the 21st day after conception, the brain and spinal cord are formed. By the end of the first month, the circulation of embryonic blood is established, the umbilical cord has formed - the connection of the embryo with the future placenta. The eye sockets, the rudiments of arms and legs appeared, the laying and development of other internal organs of the fetus is underway: the liver, kidneys, urinary tract, and digestive organs.
You no longer doubt that you are pregnant. Regardless of how you feel, all pregnant women need to visit a antenatal clinic and undergo an examination that will allow you to identify and correct existing health problems in time.
Starting from the 5th week, there may be a threat of termination of pregnancy. This will be evidenced by: periodic pain in the lower abdomen and in the lumbar region, a feeling of pressure on the rectum, an increased amount of mucus. If you experience these symptoms, you should consult a doctor.
By week 6, the face is formed in the embryo: eyes, nose, jaws and limbs.
From the 7th week of pregnancy, the yellow body of pregnancy undergoes reverse development, the production of hormones begins to be carried out by the forming placenta.
The baby develops large blood vessels, the heart becomes four-chambered. Bile ducts appear in the liver. There is a development of the endocrine glands, the brain. The auricles are already formed, fingers have appeared on the limbs. The embryo begins to move. At week 8, under the influence of the Y chromosome, the formation of male gonads (testicles) occurs. They begin to produce testosterone - the male sex hormone, which will lead to the formation of the sexual characteristics of the boy.
Your metabolism is changing significantly to provide the growing body with all the necessary "building materials" - amino acids, energy. Disadaptation to such a restructuring can result in toxicosis of the 1st half of pregnancy. It is characterized by nausea, vomiting, salivation, weight loss. When the first symptoms appear, consult a doctor.
At the tenth week, the development of the oral cavity, intestines, rectum, and bile ducts ends in the embryo. The formation of the face and hemispheres of the brain was completed. The development of the cerebellum, the main coordinator of movements, begins.
The body has adapted to the new conditions. By this time, nausea, vomiting, salivation practically disappear. You become balanced, calm. After 12 weeks, the growth of the uterus becomes noticeable
By this time, the formation of the main organs of the unborn child is completed. In appearance, the fetus resembles a small person.
A change in skin pigmentation is possible - the midline of the abdomen, nipples and the skin around them have darkened. These phenomena should pass soon after childbirth. The formation of the placenta ends. The fetus and placenta represent a single functional system. During this period of pregnancy, the fetus floats freely in the amniotic fluid. The composition of the amniotic fluid can determine the condition of the fetus.
These days, your unborn child begins to move. His limbs, ligamentous apparatus, cerebellum have already developed enough. By this time, the formation of the immune system is completed.
There have been big changes in your body. The pulse quickened, cardiac output increased significantly (40% higher than the initial level) and the volume of circulating blood (almost 500 ml).
Due to the increased volume of plasma compared to the mass of red blood cells, hemoglobin decreases in blood tests.
Some women during this period experience frequent and painful urination, pain in the lumbar region on the right or left, weakness. A large uterus presses down on the bladder, the mouth of the ureters, disrupting the outflow of urine. Stagnation of urine and incomplete emptying of the renal pelvis create conditions for the development of infection. Bacteriuria develops and pyelonephritis of pregnant women may occur. If there is any suspicion of pyelonephritis, you should immediately consult a doctor, because this disease is not only dangerous for your health, but also for the further growth and development of the fetus.
The weight of the baby is 300-350 grams, he often and quite actively moves, swallows amniotic fluid, begins to open his eyes.
In these weeks, the fetus already has a mass of 400-500 grams, and it develops very intensively bones and muscles, which require calcium from your body. Therefore, if you do not want to lose your white-toothed smile, then, on the advice of your obstetrician-gynecologist, start taking calcium supplements regularly. This will help save your teeth and get rid of leg cramps. They appear for the same reason of calcium deficiency.
At this time, the weight of the fetus is 500-600 g. It already has all the organs and systems fully formed. Until that time, only his lungs remained immature. And now, by 24 weeks, they begin to ripen. And the cells lining the lung alveoli produce surfactant, a substance that, by lubricating the alveoli, prevents them from sticking together during breathing. However, the amount of surfactant is so small that a child born at this time will not be able to breathe on its own. To survive outside the uterus, he needs sophisticated breathing equipment, incubators, a control system, infusors for nutrition, infusion media, artificial surfactant.
There are perinatal centers where children born during these terms of pregnancy are nursed. It is very difficult. And therefore, the longer the pregnancy is prolonged, the more likely the birth of a healthy and viable child. Therefore, try to do everything so that the child is born on time, full-term and healthy.
By this gestational age, the uterus is at a height of about 24 cm above the pubic bone, and now it not only builds up muscles, but is also stretched by the fetus that completely filled its cavity.
The fetus already has a mass of 700-750 g. Due to the improvement of the brain structures in his body, a connection is established with the adrenal cortex and they begin to produce corticoids - hormones necessary for adaptation. The pituitary gland of the fetus reaches such a degree of maturity that the production of adrenocorticotropic hormone begins, which also stimulates hormonal production by the adrenal glands. In short, all forces are thrown to the upcoming "publication". But the most obvious changes in these weeks occur in the lungs - there is an increased maturation of cells that produce surfactant. However, a fetus born during this period can only survive in incubators with artificial lung ventilation, artificial feeding with special infusion media. Therefore, try to keep both him and yourself from rash steps.
At this time, it's time to start preparing for the future feeding of the child. Under the influence of placental lactogen, your breasts, that is, the mammary glands, are growing rapidly. From time to time, droplets of colostrum may appear on the nipples. Daily air baths, washing with cool water, rubbing the nipples with a rough towel will help prepare the nipples for feeding. If the nipples are flat, start to stretch them little by little.
This period completes the second trimester of pregnancy. By this time, the fetus weighs up to 1000 g and has a height of up to 35 cm. However, he still cannot live on his own, because. his lungs are not mature enough and special equipment is still needed to nurse him. During these periods of pregnancy, there is an intensive growth of the fetus, the formation of muscles. His movements become more active. Periods of movement alternate with its relatively calm state when the fetus is sleeping. With an ultrasound, you can see that he already knows how to suck his thumb and even smile!
The fundus of the uterus stands on average at a height of 27-28 cm above the womb.
The third trimester of pregnancy begins. The uterus stands at a height of 29-30 cm, it becomes more difficult for you to breathe. Now one of the most serious complications can develop - toxicosis of the second half of pregnancy, which is characterized by the appearance of edema, increased blood pressure and the appearance of protein in the urine. For early diagnosis of this complication, it is necessary to carefully observe an obstetrician-gynecologist and follow all his recommendations, incl. strict weight control. In the III trimester of pregnancy, the daily weight gain should be no more than 50 g, i.e. no more than 300 g per week. You should also monitor the ratio of drunk and secreted fluid.
Have you asked your doctor how the fetus is? Find out now it's very important. Its position can be longitudinal, transverse, oblique. Correct, normal is the longitudinal position of the fetus. Childbirth is safer with cephalic presentation. From this period of pregnancy, it is necessary to wear a prenatal bandage that will support the anterior abdominal wall and help maintain the correct position and presentation of the fetus. If the presentation of the fetus is breech, i.e. above the entrance to the pelvis is the pelvic end of the fetus, then the bandage should not be worn yet. There is gymnastics to correct the presentation of the fetus.
In the morning and evening for 1 hour, do the following: lie down on the bed on your left side and lie quietly for 15 minutes, then turn over to your right side and lie for the next 15 minutes, and then repeat these turns 2 more times.
Pregnant women with Rh-negative blood and with O (I) blood type need blood tests for Rh - or group immune antibodies. Immunization of pregnant women with Rh-negative blood is carried out from 28 weeks and within 72 hours after childbirth according to the indications, which will be discussed by the doctor observing you in the antenatal clinic.
The fetus already has a mass of 1800-2100 g, a height of 40-41 cm. By the end of this period, its lungs will begin to produce surfactant in full and will be able to breathe without special equipment. The fetus is fully developed, its chances of surviving in case of preterm birth are greatly increased. However, there is still extremely little subcutaneous fat, so his skin is thin and has a red color. Such a newborn retains heat very poorly and at birth needs an incubator or a heating pad. His body is still covered with fluff and cheese-like grease, the auricles are still very small, but they are already beginning to straighten out, the boy's testicles descend into the scrotum.
Caring for a premature baby is the hardest work for the whole family, associated with high material costs, physical overload of parents, and this work is not always rewarded, since a child can be born and remain sick. Therefore, up to 37 weeks of pregnancy, a woman should be especially attentive to her condition and, at the slightest suspicion of an increase in the tone of the uterus, starting frequent and regular contractions, immediately consult a doctor.
Doctors know that women, in anticipation of the arrival of a new person in the house, begin to glue walls and paint ceilings during this period. Don't take unnecessary risks. For this, prenatal leave is provided from 30 weeks, so that you can avoid overwork, do not push in transport, and have the opportunity to sleep. So repairs, stuffy shops, queues are no longer for you.
The fetus already has a mass of 2100-2700 g and a height of 44-45 cm. It is advisable to see a doctor during this period of pregnancy at least once every 10 days.
From this point on, your pregnancy is considered full-term. And if you have a baby in these weeks, he will live. Its development is complete. Now he has a mass of approximately 2700-3000 g. Height is 49-50 cm. The remaining two weeks he will add a little in weight and height.
It becomes easier for you to breathe, as the fetal head is pressed tightly against the entrance to the pelvis, the uterus pulls the anterior abdominal wall more, and therefore its bottom sank lower. Tension of the uterus; small sharp pulling pains in the lumbar region.
With an exacerbation of extragenital diseases, the appearance of signs of toxicosis in the second half of pregnancy, with an incorrect position of the fetus, with some gynecological diseases, against which pregnancy develops, a scar on the uterus, etc., early prenatal hospitalization is required. Do not forget to take an exchange card, passport, medical insurance policy and birth certificate to the hospital.
You can find out the approximate day of delivery by the date of the last normal menstruation - count back three months and add 7 days. The resulting number will be the estimated date of birth. More precisely, according to many parameters, ultrasound data, additional studies, the date of the first fetal movement, the date of the first visit to the obstetrician-gynecologist, especially if the visit was before 11-12 weeks of pregnancy.
The child already has all the signs of maturity. His weight is more than 3000 g, and his height is more than 50 cm, he has fair skin, a sufficient amount of subcutaneous fat, he retains heat and does not need special heating. He will scream loudly, breathe, suck. There is a very small amount of lubricant on the skin, which will no longer be able to protect it from the effects of amniotic fluid.
For you, regular contractions (1 contraction every 10 minutes) will become an indicator of the beginning of the birth process, or you will feel the outflow of amniotic fluid, you will see scanty bloody discharge - do not panic, call an ambulance, the telephone number for transportation for pregnant women is written on the margins of your exchange card. While she is driving, change your clothes, prepare your passport, exchange card, medical insurance policy and birth certificate.
Critical stages of pregnancy - why are they dangerous?
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The wonderful period of waiting for a baby for almost every woman is far from serene: how many worries, worries and doubts arise in expectant mothers at this time - they simply cannot be counted. In most cases, all fears are in vain - the baby develops and grows safely. However, it must be remembered that there are also so-called critical periods of pregnancy, when inattention to oneself and one's body can lead to a disastrous result - its spontaneous termination.
The beginning of a new life in a woman's body, or 2-3 weeks of pregnancy, is considered the first critical period. This is due to the fact that the egg can be fertilized, but due to changes as a result of inflammation, hormonal imbalances, the presence of nodes, scars, fibroids or synechia on the inner mucous membrane of the uterus, implantation does not occur, the embryo dies and is removed from the mother's body during menses. However, even if implantation has occurred, the embryo may stop developing and spontaneous miscarriage at an early stage , and the main reason for this course of events is chromosomal abnormalities.
The second critical period of the first trimester begins at 8 and ends at 12 weeks of gestation. At this time, the main cause of interruption is considered to be hormonal deficiency, which disrupts the process of placental formation. This condition may be associated with reduced work of the corpus luteum of the ovaries, excessive production of androgens by the adrenal glands - male sex hormones, as well as malfunctions of the pituitary gland or thyroid gland. The threat of termination of pregnancy can be eliminated with the help of properly selected and timely prescribed hormonal treatment, which will allow the baby to safely reach the due date.
In addition, throughout the first trimester of pregnancy, the fetus may stop developing due to the following unfavorable environmental factors:
harmful working conditions
physical effects - radiation, vibration, intense sports training, etc.
acute infectious diseases (influenza, cytomegalovirus, herpes, rubella and others)
severe stressful situations
And even if the fetus develops further, the negative impact of most of these factors can appear after a few months of pregnancy or even after the baby is born: these can be anatomical disorders or severe malformations. Therefore, the entire first trimester of the development of a new life can be considered "critical".
The third critical period of pregnancy occurs at 18-24 weeks of gestation and is largely associated with the active growth of the uterus. At this time, spontaneous interruption most often occurs due to isthmic-cervical insufficiency (ICI), as a result of which the fetal egg descends under the influence of gravity, loses its integrity and triggers the mechanism of labor activity. However, shortening and expansion of the cervical canal, detected in time, allows suturing the cervix or installing an obstetric pessary and safely prolonging the pregnancy. Here we should also remember about infectious diseases, including intrauterine infection, which can disrupt the functions of the placenta, lead to the outflow of water from the fetal bladder and late miscarriage.
Another common reason for interrupting the process of gestation at this time is placenta previa or its low location: for various reasons, it can exfoliate, cause severe bleeding and death of the fetus. In addition, at this time, pregnancy may stop developing due to violations in the development of the brain and the most important functional systems of the baby, caused by the harmful effects of various negative factors on them in the first trimester.
In this trimester - at 28-32 weeks - the fourth critical period takes place. The threat of premature birth may occur due to insufficiency of the placenta, its premature detachment, severe forms of late toxicosis of pregnant women, ICI and various hormonal disorders. In addition, due to the overdistension of the uterus, most multiple pregnancies end at this time. Children born during this period are already viable, but they need long-term qualified medical care.
In addition to all the periods listed above, the critical periods for women who have had reproductive losses in the past are the days of planned menstruation, miscarriages or “fading” of pregnancies. Doctors believe that during these periods the body can “remember” the need for hormonal changes, so they carefully monitor the condition of the expectant mother and baby and prescribe treatment in a timely manner if any threat arises.