Picture of fetus at 4 weeks. Fetal Development: A Comprehensive Guide to Your Baby’s Growth Month by Month

13.10.202215.07.2023 by alexxlab

How does a single cell transform into a fully-formed baby. What are the key milestones in fetal development. When can you first detect a heartbeat. At what stage do organs begin to form.

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The Miraculous Journey from Conception to Birth

The process of fetal development is a remarkable journey that begins with a single cell and culminates in the birth of a fully-formed baby. This article provides a detailed look at the various stages of fetal growth, highlighting key milestones and offering insights into the intricate process of human development.

Early Stages: From Zygote to Embryo

The journey begins with fertilization, also known as conception. When does this process occur? Fertilization happens when a sperm cell successfully joins with an egg, forming a single cell called a zygote. This zygote contains DNA from both parents and marks the very beginning of a new life.

What happens in the days following fertilization? Within about 3 days, the zygote begins dividing into multiple cells. By day 5 or 6, it has traveled through the fallopian tube and reached the uterus. At this point, it’s referred to as a blastocyst.

The blastocyst then attaches to the uterus wall in a process called implantation. This typically occurs around 10-12 days after fertilization. At this stage, the developing organism is now called an embryo.

Key Developments in the Embryonic Stage

Formation of structures that will become the face and neck
Continued development of the heart and blood vessels
Initial development of lungs, stomach, and liver
Formation of the placenta, which will nourish the growing fetus

Is it possible to detect pregnancy at this early stage? Yes, a home pregnancy test could show a positive result as early as 10-12 days after conception.

The First Trimester: Rapid Growth and Development

The first trimester, which spans from week 1 to week 12 of pregnancy, is a period of rapid development for the embryo, which becomes a fetus at the end of the 10th week.

Weeks 4-8: Laying the Foundation

By week 8, the embryo has grown to just over half an inch in size. What structures are forming at this stage? Eyelids and ears are beginning to take shape, and the tip of the nose is visible. The arms and legs are well-formed, with fingers and toes growing longer and more distinct.

Weeks 9-12: The Transition to Fetus

At the end of the 10th week, the embryo is now considered a fetus. How big is the fetus at this point? It measures about 2 inches and has started to make its own movements. The sex organs are beginning to become clear, and the heartbeat may be audible with special instruments.

Second Trimester: Visible Growth and Increased Movement

The second trimester, spanning weeks 13 to 26, is often considered the most comfortable period of pregnancy for many women. It’s also a time of significant growth and development for the fetus.

Weeks 13-16: Rapid Growth and Development

By week 16, the fetus measures about 4.3 to 4.6 inches and weighs approximately 3.5 ounces. What developments occur during this period? The eyes can now blink, and the heart and blood vessels are fully formed. Fingerprints have developed on the fingers and toes.

Weeks 17-20: The Halfway Point

At 20 weeks, the fetus weighs about 10 ounces and is a little more than 6 inches long. This is typically when an ultrasound is performed to check on the fetus’s growth and development. Can you determine the baby’s sex at this point? Yes, in most cases, it’s possible to determine whether it’s a boy or a girl during the 20-week ultrasound.

Weeks 21-26: Increased Movement and Sensory Development

By week 24, the fetus weighs about 1.4 pounds and can respond to sounds by moving or increasing its pulse rate. The inner ear is fully developed, allowing the fetus to potentially sense its position in the womb.

Third Trimester: Final Preparations for Birth

The third trimester, from week 27 to birth, is a period of rapid weight gain and final organ maturation for the fetus.

Weeks 27-31: Viability and Continued Growth

At 28 weeks, the fetus weighs about 2 pounds and 6 ounces. What’s significant about this stage? If born prematurely at this point, there’s a good chance of survival with proper medical care.

Weeks 32-36: Rapid Weight Gain

By 32 weeks, the fetus weighs almost 4 pounds and moves frequently. A layer of fat begins to form under the skin, giving the fetus a smoother appearance. Between now and delivery, the fetus will gain up to half of its birth weight.

Weeks 37-40: Preparing for Birth

At 37 weeks, the average fetus is about 18.5 inches long and weighs close to 6 pounds. The brain has been developing rapidly, and the lungs are almost fully mature. Typically, the head is positioned down into the pelvis in preparation for birth.

Understanding Pregnancy Duration and Due Dates

How is a due date calculated? The due date is typically calculated using the first day of the last menstrual period. Based on this, pregnancy can last between 38 and 42 weeks, with 40 weeks being considered full term.

Are all pregnancies that go beyond 42 weeks truly “late”? Not necessarily. Some post-term pregnancies may be due to an inaccurate due date calculation. For safety reasons, most babies are delivered by 42 weeks, sometimes requiring induction of labor.

The Marvels of Modern Prenatal Imaging

Advancements in medical technology have revolutionized our ability to visualize fetal development. How have ultrasound techniques improved? Traditional 2D ultrasounds provide flat, black-and-white images, while newer 4D ultrasounds offer moving 3D images in real-time, allowing parents to see their baby’s movements and facial expressions.

These imaging techniques not only provide cherished memories for expectant parents but also serve crucial medical purposes. They allow healthcare providers to monitor fetal growth, check for potential abnormalities, and ensure the health of both the fetus and the placenta throughout pregnancy.

Pictures of Fetal Development Month by Month

Reviewed by Traci C. Johnson, MD on May 09, 2023

Are you curious about what’s going on in your uterus during pregnancy? Take a peek inside to see all that’s happening with your fetus and your body — and what to expect as your pregnancy progresses.

When a sperm joins with an egg, the two form a single cell called a zygote that contains DNA from both parents. This is fertilization, also called conception. Within about 3 days, the zygote begins dividing into more cells. By about 5-6 days, it has traveled through the fallopian tube into the uterus. At this stage, it’s called a blastocyst. It attaches, or implants, to the uterus walls. By day 10-12, the zygote has become an embryo.

At this point, the embryo is developing the structures that will eventually form the face and neck. The heart and blood vessels continue to develop. And the lungs, stomach, and liver start to develop. The placenta, which will nourish the fetus, is forming. A home pregnancy test could show up positive now.

The embryo is now a little over half an inch in size. Eyelids and ears are forming, and you can see the tip of the nose. The arms and legs are well formed. The fingers and toes grow longer and more distinct. At the end of the 10th week of pregnancy, the embryo is considered a fetus. That’s what doctors call it until birth.

The fetus measures about 2 inches and starts to make its own movements. You may start to feel the top of your uterus above your pubic bone. Your doctor may hear the heartbeat with special instruments. The sex organs should start to become clear. At the end of the 12th week, the first trimester is over.

The fetus now measures about 4.3 to 4.6 inches and weighs about 3.5 ounces. You should be able to feel the top of your uterus about 3 inches below your belly button. The fetus’ eyes can blink and the heart and blood vessels are fully formed. Its fingers and toes have fingerprints.

The fetus weighs about 10 ounces and is a little more than 6 inches long. Your uterus should be at the level of your belly button. The fetus can suck its thumb, yawn, stretch, and make faces. Soon — if you haven’t already — you’ll feel it move, which is called “quickening.”

An ultrasound is usually done at 20 weeks. During this ultrasound, the doctor will make sure that the placenta is healthy and attached normally and that your fetus is growing properly. You can see the heartbeat and movement of its body, arms, and legs on the ultrasound. You can usually find out whether it’s a boy or a girl at 20 weeks.

Shown here is a 2D ultrasound (inset) contrasted with a 4D ultrasound, both at 20 weeks.

The fetus weighs about 1.4 pounds now and responds to sounds by moving or increasing their pulse. You may notice jerking motions if they hiccup. With the inner ear fully developed, it may be able to sense being upside down in the womb.

The fetus weighs about 2 pounds and 6 ounces and changes position often at this point in pregnancy. If you had to deliver prematurely now, there is a good chance it would survive. Ask your doctor about preterm labor warning signs. With the third trimester beginning, now is the time to register for birthing classes. They prepare you for many aspects of childbirth, including labor and delivery and taking care of your newborn.

The fetus weighs almost 4 pounds and moves often. It has fewer wrinkles as a layer of fat starts to form under the skin. Between now and delivery, your fetus gains up to half its birth weight. Think about how you plan to feed your baby. You may notice a yellowish fluid leaking from your breasts. That’s colostrum, and it happens to prepare your breasts for making milk. Most people go to the doctor every 2 weeks at this stage.

A fetus’ size depends on things like gender, the parents’ size, and whether it’s a multiple. On average, it’s about 18.5 inches and weighs close to 6 pounds. The brain has been developing rapidly. Lungs are almost fully developed. The head is usually positioned down into the pelvis. A baby is considered early-term if born between 37-39 weeks, at term at 39-40 weeks, and late term at 41-42 weeks.

Your due date marks the end of your 40th week. The delivery date is calculated using the first day of your last period. Based on this, pregnancy can last between 38 and 42 weeks. Some post-term pregnancies — those lasting more than 42 weeks — aren’t actually late. The due date may just may not have been accurate. For safety reasons, most babies are delivered by 42 weeks. Sometimes the doctor may need to induce labor to make that happen.

IMAGES PROVIDED BY:

(2) Dr. David M. Phillips / Visuals Unlimited / Getty Images
(3) 3D4Medical.com / Getty Images
(4) Copyright © Scott Camazine / Phototake — All rights reserved.
(5) Copyright © LookatSciences / Phototake – All rights reserved.
(6) Nestle / Petit Format / Photo Researchers, Inc.
(7) © Lennart Nilsson Photography AB. All rights reserved worldwide.
(8) a) Dr.Benoit/Mona Lisa. Copyright © LookatSciences / Phototake — All rights reserved. b)Vincenzo Lombardo / Photographer’s Choice / Getty Images
(9) Dr. Benoit/Mona Lisa. Copyright © LookatSciences / Phototake — All rights reserved.
(10) © Lennart Nilsson Photography AB. All rights reserved worldwide.
(11) Jose Manuel Gelpi Diaz / iStockphoto
(12) © Lennart Nilsson Photography AB. All rights reserved worldwide.
(13) © Yoav Levy / Phototake — All rights reserved.

SOURCES:

American Academy of Family Physicians.

Cleveland Clinic: “Fetal Development.”

Mayo Clinic: “Fetal development: The 1st trimester,” “Blastocyst.”

Merck Manual: “Stages of Development of the Fetus.”

University of Rochester Medical Center: “Anatomy of the Male and Female Pelvis.”American College of Obstetricians and Gynecologists: “Definition of Term Pregnancy,” “How Your Baby Grows During Pregnancy.”

KidsHealth.org: “Pregnancy Calendar.”

March of Dimes: “Prenatal Care – Ultrasound,” “What Is Full-Term?”

U.S. Department of Health and Human Services Office of Women’s Health: “Pregnancy: Breast Changes. “

Fetal development by week: Your baby in the womb

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From conception to labor, your baby is constantly growing and developing. Your baby moves through different stages, starting as a blastocyst, then maturing into an embryo, and then a fetus. Around the 5 week mark, cells in your baby’s future heart will begin to flicker. At 27 weeks they’ll have regular sleep and wake cycles, and at 39 weeks your baby is physically developed. Use this timeline to learn how big your baby is, plus how they’re developing throughout pregnancy.

Follow your baby’s development week by week, from conception to labor, in these amazingly detailed, doctor-reviewed images.

2 weeks: Fertilization

At the start of this week, you ovulate. Your egg is fertilized 12 to 24 hours later if a sperm penetrates it. Over the next several days, the fertilized egg will start dividing into multiple cells as it travels down the fallopian tube, enters your uterus, and starts to burrow into the uterine lining.

Read about fertilization.

3 weeks: Implantation

Now nestled in the nutrient-rich lining of your uterus is a microscopic ball of hundreds of rapidly multiplying cells that will develop into your baby. This ball of cells, called a blastocyst, has begun to produce the pregnancy hormone hCG, which tells your ovaries to stop releasing eggs.

Read about implantation.

4 weeks

Your ball of cells is now officially an embryo. You’re now about 4 weeks from the beginning of your last period. It’s around this time – when your next period would normally be due – that you might be able to get a positive result on a home pregnancy test.

Your baby is the size of a poppy seed.

Read about your pregnancy at 4 weeks.

5 weeks

Your baby resembles a tadpole more than a human, but is growing fast. The circulatory system is beginning to form, and cells in the tiny “heart” will start to flicker this week.

Your baby is the size of a sesame seed.

Read about your pregnancy at 5 weeks.

6 weeks

Your baby’s nose, mouth and ears are starting to take shape, and their intestines and brain are beginning to develop.

Your baby is the size of a lentil.

Read about your pregnancy at 6 weeks.

7 weeks

Your baby has doubled in size since last week, but still has a tail, which will soon disappear. Little hands and feet that look more like paddles are emerging from the developing arms and legs.

Your baby is the size of a blueberry.

Read about your pregnancy at 7 weeks.

8 weeks

Your baby has started moving around, though you won’t feel your baby move yet. Nerve cells are branching out, forming primitive neural pathways. Breathing tubes now extend from their throat to their developing lungs.

Your baby is the size of a kidney bean.

Read about your pregnancy at 8 weeks.

9 weeks

Your baby’s basic anatomy is developing (they even have tiny earlobes now), but there’s much more to come. Their embryonic tail has disappeared and they weigh just a fraction of an ounce but are about to start gaining weight fast.

Your baby is the size of a grape.

Read about your pregnancy at 9 weeks.

10 weeks

Your embryo has completed the most critical portion of development. Their skin is still translucent, but their tiny limbs can bend and fine details like nails are starting to form.

Your baby is the size of a kumquat

Read about your pregnancy at 10 weeks.

11 weeks

Your baby is almost fully formed. They’re kicking, stretching, and even hiccupping as their diaphragm develops, although you can’t feel any activity yet.

Your baby is the size of a fig.

Read about your pregnancy at 11 weeks.

12 weeks

This week your baby’s reflexes kick in: Their fingers will soon begin to open and close, toes will curl, and their mouth will make sucking movements.

Your baby is the size of a lime.

Read about your pregnancy at 12 weeks.

13 weeks

This is the last week of your first trimester. Your baby’s tiny fingers now have fingerprints, and their veins and organs are clearly visible through their skin. If you’re having a girl, her ovaries contain more than 2 million eggs.

Your baby is the size of a pea pod.

Read about your pregnancy at 13 weeks.

Entering the second trimester: What lies ahead

In this illustration, you can see how big – and yet, how tiny still – your baby is as you begin your second trimester.

After the first trimester, a miscarriage is much less likely. And for many moms-to-be, early pregnancy symptoms like morning sickness and fatigue have faded away. If you’re feeling more energetic now and haven’t been exercising, it’s a good time to start a regular pregnancy fitness routine.

Plus: See our ultimate pregnancy to-do list for the second trimester

14 weeks

Your baby’s brain impulses have begun to fire and they’re using their facial muscles. Their kidneys are working now, too. If you have an ultrasound, you may even see them sucking their thumb.

Your baby is the size of a lemon.

Read about your pregnancy at 14 weeks.

15 weeks

Your baby’s eyelids are still fused shut, but they can sense light. If you shine a flashlight on your tummy, they’ll move away from the beam. Ultrasounds done this week may reveal your baby’s sex.

Your baby is the size of an apple.

Read about your pregnancy at 15 weeks.

16 weeks

The patterning on your baby’s scalp has begun, though their hair isn’t visible yet. Their legs are more developed, their head is more upright, and their ears are close to their final position.

Your baby is the size of an avocado.

Read about your pregnancy at 16 weeks.

17 weeks

Your baby can move their joints, and their skeleton – formerly soft cartilage – is now hardening to bone. The umbilical cord is growing stronger and thicker.

Your baby is the size of a turnip.

Read about your pregnancy at 17 weeks.

18 weeks

Your baby is flexing their arms and legs, and you may be able to feel those movements. Internally, a protective coating of myelin is forming around their nerves.

Your baby is the size of a bell pepper.

Read about your pregnancy at 18 weeks.

19 weeks

Your baby’s senses – smell, vision, touch, taste and hearing – are developing and they may be able to hear your voice. Talk, sing or read out loud to them, if you feel like it.

Your baby is the size of an heirloom tomato.

Read about your pregnancy at 19 weeks.

20 weeks

Your baby can swallow now and their digestive system is producing meconium, the dark, sticky goo that they’ll pass in their first poop – either in their diaper or in the womb during delivery.

Your baby is the size of a banana.

Read about your pregnancy at 20 weeks.

21 weeks

Your baby’s movements have gone from flutters to full-on kicks and jabs against the walls of your womb. You may start to notice patterns as you become more familiar with their activity.

Your baby is the size of a carrot.

Read about your pregnancy at 21 weeks.

22 weeks

Your baby now looks almost like a miniature newborn. Features such as lips and eyebrows are more distinct, but the pigment that will color their eyes isn’t present yet.

Your baby is the size of a spaghetti squash.

Read about your pregnancy at 22 weeks.

23 weeks

Your baby’s ears are getting better at picking up sounds. After birth, they may recognize some noises outside the womb that they’re hearing inside now.

Your baby is the size of a large mango.

Read about your pregnancy at 23 weeks.

24 weeks

Your baby cuts a pretty long and lean figure, but chubbier times are coming. Their skin is still thin and translucent, but that will begin to change soon too.

Your baby is the size of an ear of corn.

Read about your pregnancy at 24 weeks.

25 weeks

Your baby’s wrinkled skin is starting to fill out with baby fat, making them look more like a newborn. Their hair is beginning to come in, and it has color and texture.

Your baby is now the same weight as an average rutabaga.

Read about your pregnancy at 25 weeks.

26 weeks

Your baby is now inhaling and exhaling amniotic fluid, which helps develop their lungs. These breathing movements are good practice for that first breath of air at birth.

Your baby is the size of a bunch of scallions.

Read about your pregnancy at 26 weeks.

27 weeks

This is the last week of your second trimester. Your baby now sleeps and wakes on a regular schedule, and their brain is very active. Their lungs aren’t fully formed, but they could function outside the womb with medical help.

Your baby is the size of a head of cauliflower.

Read about your pregnancy at 27 weeks.

Entering the third trimester: What lies ahead

In this illustration, you’ll notice that your growing baby takes up quite a bit of room these days. In the third trimester, you might be peeing more often or have leg cramps as they press on nerves in your hips and back.

Now’s the time to do things like sign up for a childbirth class, choose a doctor for your baby, and create a baby registry, if you haven’t done so already.

28 weeks

Your baby’s eyesight is developing, which may enable them to sense light filtering in from the outside. They can blink, and their eyelashes have grown in.

Your baby is the size of a large eggplant.

Read about your pregnancy at 28 weeks.

29 weeks

Your baby’s muscles and lungs are busy getting ready to function in the outside world, and their head is growing to make room for their developing brain.

Your baby is the size of a butternut squash.

Read about your pregnancy at 29 weeks.

30 weeks

Your baby is surrounded by a pint and a half of amniotic fluid, although there will be less of it as they grow and claim more space inside your uterus.

Your baby is the size of a large cabbage.

Read about your pregnancy at 30 weeks.

31 weeks

Your baby can now turn their head from side to side. A protective layer of fat is accumulating under their skin, filling out their arms and legs.

Your baby is the size of a coconut.

Read about your pregnancy at 31 weeks.

32 weeks

You’re probably gaining about a pound a week now. Half of that goes straight to your baby, who will gain one-third to half their birth weight in the next seven weeks in preparation for life outside the womb.

Your baby is the size of a large jicama.

Read about your pregnancy at 32 weeks.

33 weeks

The bones in your baby’s skull aren’t fused yet. That allows them to shift as their head squeezes through the birth canal. They won’t fully fuse until adulthood.

Your baby is the size of a pineapple.

Read about your pregnancy at 33 weeks.

34 weeks

Your baby’s central nervous system is maturing, as are their lungs. Babies born between 34 and 37 weeks who have no other health problems usually do well in the long run.

Your baby is the size of a cantaloupe.

Read about your pregnancy at 34 weeks.

35 weeks

It’s getting snug inside your womb – but you should still feel your baby moving as much as ever. Your baby’s kidneys are fully developed, and their liver can process some waste products.

Your baby is the size of a honeydew melon.

Read about your pregnancy at 35 weeks.

36 weeks

Your baby is gaining about an ounce a day. They’re also losing most of their lanugo hair that covered their body, along with the vernix caseosa, a waxy substance that was protecting their skin until now.

Your baby is the size of a head of romaine lettuce.

Read about your pregnancy at 36 weeks.

37 weeks

Your due date is very close, and though your baby looks like a newborn, they’re not considered full-term until 39 weeks. Over the next two weeks, their lungs and brain will continue to mature.

Your baby is the size of a bunch of Swiss chard.

Read about your pregnancy at 37 weeks.

38 weeks

Are you curious about your baby’s eye color? Their irises aren’t fully pigmented at birth, so their eyes could change color up until they’re about a year old.

Your baby is the size of a leek.

Read about your pregnancy at 38 weeks.

Turning full term

At 39 weeks, your baby will be considered full-term. In the illustration, you can see the mucus plug sealing your uterus and how squished your intestines are now.

39 weeks

Your baby’s physical development is complete, but they’re still busy putting on fat and growing bigger.

Your baby is the size of a mini watermelon.

Read about your pregnancy at 39 weeks.

40 weeks

If you’re past your due date, you may not be as late as you think, especially if you calculated it solely based on the day of your last period. Sometimes women ovulate later than expected.

Your provider will continuously assess your pregnancy to make sure you can safely continue your pregnancy.

Your baby is the size of a small pumpkin.

Read about your pregnancy at 40 weeks.

41 weeks

Your baby is now considered late-term. Going more than two weeks past your due date can put you and your baby at risk for complications, so your provider will probably talk to you about inducing labor. They may perform a non-stress test (NST) to monitor your baby’s fetal heart rate and your contractions to make sure your baby isn’t in any distress.

Read about your pregnancy at 41 weeks.

Labor and delivery

Meeting your baby for the first time is so exciting – but exactly what will lead up to that moment is unpredictable, and it’s natural to feel nervous. Here’s some help as you prepare for the big day. Find out how you’ll know you’re in labor and what to expect from delivery:

Learn the signs of labor and stages of labor

Read when to go to the hospital for labor

Take our free childbirth class

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Kate Marple

Kate Marple is a writer and editor who specializes in health, pregnancy, and parenting content. She’s passionate about translating complicated medical information into helpful pregnancy and parenting advice that’s easy to understand. She lives in San Francisco with her family.

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My pregnancy week by week

weeks pregnant

Pregnancy 4 weeks description and photo – Euromedclinic 24

This week the baby’s growth is from 0. 36 mm to 1 mm. The period of development that began at week 4 is called “embryonic”, it will last until the beginning of the eleventh week of your pregnancy. The fourth week is extremely important for the unborn baby, now all his organs are beginning to form, and some of them will even begin to function! Embryonic petals begin to form, which will subsequently develop into various tissues and organs. The inner layer, or endoderm, serves as the basis for the formation of the lungs, digestive system, liver and pancreas. The middle layer, or mesoderm, will be transformed into the bone, muscle and circulatory systems, heart and kidneys. The outer layer, or ectoderm, will develop further into hair, skin, nervous system, eye lenses, tooth enamel. The head of the embryo also begins to form. Now it is a small droplet, tender and transparent.

In addition, on the 4th week there is an active development of extra-embryonic organs – amnion, chorion, yolk sac. It is these organs that will provide breathing, nutrition, protection and support for your baby. The amnion will become the basis for the development of the fetal bladder, and the chorion – the placenta. In general, the most important weeks in the development of an unborn child are from 1 to 12, at which time not only internal organs are formed, but also the placenta, which plays a huge role in providing the baby with nutrition, oxygen, and also in the production of hormones.

What is the “yellow body” and what is its role?

The ovum leaves the ovary after ovulation, and in the place where the ruptured follicle remained, a corpus luteum, or corpus luteum, is formed. Outwardly, it looks like a small bubble or sac, which contains liquid and is located on the wall of the ovary. The corpus luteum rapidly develops blood vessels designed to produce hormones, in particular progesterone. The hormones will keep the pregnancy going early until the placenta separates.

Physicians have not yet come to a consensus on the role of the corpus luteum. There is a point of view that it plays an important role at the beginning of pregnancy, supplying the body with progesterone. Starting from 8-12 weeks, the placenta begins to supply progesterone, and the corpus luteum, as a rule, functions for about 6 months. However, there are cases when the corpus luteum persisted until childbirth. In addition, there are a number of cases when the corpus luteum had to be removed during the implantation period due to a ruptured cyst, while the pregnancy proceeded and ended quite successfully.

Changes in a woman’s body

You should have started your period by the end of this week. The delay confuses you, you start to suspect something. And then he also feels a little nauseous, and for some reason the temperature rises for no apparent reason. Yes, and she became irritable … Have you still not bought a pregnancy test? Then now is the time!

What to do in the fourth week of pregnancy

If you want, take a blood test for the hormone hCG (chorionic gonadotropin), its level in the blood rises already 10 days after fertilization. This analysis will be the most informative and will definitely let you know whether you are pregnant or not.

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Ultrasound photo during pregnancy, fetal photo during ultrasound during pregnancy

4-5 weeks

Photo ultrasound of the fetus during pregnancy 4-5 weeks

The earliest period at which a fetal egg in the uterine cavity can be seen using transvaginal ultrasound is the 30th day of gestation, or 4-5 obstetric weeks of pregnancy. The level of hCG blood in this case should be at least 1000 mU / ml. At this time, neither the embryo nor the yolk sac is visible. When visualizing two fetal eggs, it can be argued that this is a dichorionic multiple pregnancy. When visualizing one fetal egg, it can be argued that this is a monochorionic pregnancy. But at this time, we still cannot say how many embryos are in each fetal egg. In addition, during a single ultrasound, we still cannot tell if this pregnancy is progressing, since the embryo does not yet have a heartbeat. The average inner diameter (SID) of the fetal egg at this time is 2-10 mm.

The conclusion will indicate: Uterine pregnancy of a short term.

More about ultrasound in early pregnancy

5-6 weeks

Photo ultrasound of the fetus during pregnancy 5-6 weeks

At this time, a white ring appears inside the fetal egg – this is the yolk sac.

Foci of erythropoiesis form in the wall of the yolk sac, which form a capillary network, supplying erythroblasts (nuclear erythrocytes) to the primary circulatory system of the fetus. The yolk sac is a source of primary germ cells that migrate from its wall to the anlage of the gonads of the embryo. Until the 6th week after fertilization, the yolk sac, playing the role of the “primary liver”, produces many important proteins for the embryo – alpha-fetoprotein, transferrins, alpha2-microglobulin. By the end of the first trimester of pregnancy, this provisional organ ceases to function and is reduced.

The normal size of the yolk sac is 2-6 mm. If two yolk sacs are visualized in the fetal egg, then this is a monochorionic multiple pregnancy. But if one yolk sac is visible inside the fetal egg, and the embryo is not yet clearly visualized, then this may still be monochorionic monoamniotic twins.

At the beginning of the 5th week, the embryo is practically indistinguishable on the wall of the yolk sac, but by the end of the week, the coccyx-parietal size (CTE) of the embryo reaches 3 mm.

SVD of the ovum 11-16 mm.

Read also: Is ultrasound harmful during pregnancy? Is ultrasound dangerous? How often can an ultrasound be done?

6 – 7 weeks

Photo ultrasound of the fetus during pregnancy 6-7 weeks

Inside the fetal egg, we see a “ringlet with a precious stone” 🙂 – this is the yolk sac and already a well-defined embryo, located nearby. The heart of the embryo begins to beat at the beginning of the 6th obstetric week of pregnancy. It is the presence of a heart pulsation that is a reliable ultrasound sign of a progressing pregnancy. With CTE ≥6 mm and the absence of heart pulsation, a conclusion is made about stopping the development of this embryo. Normal heart rate (HR) of the embryo at the very beginning of the 6th week 70-90 beats per minute, but by the end of the week it becomes more than 100 beats. in min. In the early stages of pregnancy, it is not the heart rate that matters, but the presence or absence of heart contractions as such. Sometimes, with a non-developing pregnancy, you can see the reflection of the pulsation of the mother’s vessels inside the embryo and take them for the baby’s heartbeat. But in this case, the pulsation frequency will be identical to the mother’s heart rate.

The presence of one yolk sac, one embryo and one pulsating heart in most cases indicates a singleton pregnancy. But in very rare cases, it may later turn out to be unseparated twins.

SVD of the ovum 13-23 mm. Embryo KTR 4-9 mm.

Read also: “I don’t want an ultrasound, I want a baby!”. Why is ultrasound during pregnancy necessary?

7 – 8 weeks

Photo ultrasound of the fetus during pregnancy 7-8 weeks

The distance between the embryo and the yolk sac gradually increases and the yolk duct (ductus vitellinus), which connects the yolk sac and the intestines of the embryo, becomes clearly visible. Just like the yolk sac, the duct becomes empty and resolves at a later date, but if this does not happen for some reason, then a blind protrusion of the ileum wall is formed in a person – Meckel’s diverticulum.

Until this time, the chorion has an annular shape, surrounds the fetal egg from all sides, and it is still impossible to say which wall of the uterus the embryo has attached to.

In the case of monochorionic twins, no amniotic membranes are yet visible, and in the presence of two yolk sacs, it is still impossible to tell whether this pregnancy is mono or diamniotic. If the gestational sac contains two yolk sacs and two fetuses with cardiac activity, the subsequent number of amniotic cavities may be greater than the number of placentas (monochorial diamniotic) or the same (monochorial monoamniotic). In this case, it is possible to accurately determine amnionality after 8 weeks, when the amniotic membranes begin to be clearly visualized.

Embryo heart rate 130-160 beats per minute.

SVD of the ovum 24-30 mm, CTE of the embryo 9-15 mm.

8 – 9 weeks

Photo ultrasound of the fetus during pregnancy 8-9 weeks

During the ultrasound of the embryo, it is already possible to clearly distinguish individual segments – the head, trunk, limbs. The first movement appears. The amniotic membranes become clearly visible and we can already talk about the number of amniotic sacs in multiple pregnancies. The chorion is differentiated into a smooth one, facing the uterine cavity, and a branched one, from which the placenta will subsequently form, so that we can already talk about the predominant location of the chorion along the anterior or posterior wall of the uterus.

The heart rate of the embryo increases to 160-180 beats per minute.

SVD of the ovum 31-37 mm. Embryo KTR 16-22 mm.

9 – 10 weeks

Photo ultrasound of the fetus during pregnancy 9-10 weeks

The development of the embryo continues. The handles of the legs are already clearly visible, and on a good device, sometimes you can even see the fingers and toes.