Week 5 embryo development
You and your baby at 5 weeks pregnant
Your baby at 5 weeks
Your baby's nervous system is already developing, and the foundations for its major organs are in place. At this stage, the embryo is around 2mm long.
The heart is forming as a simple tube-like structure. Your baby already has some of its own blood vessels and blood begins to circulate.
A string of these blood vessels connects you to your baby and will become the umbilical cord.
At the same time, the embryo's outer layer of cells develops a groove and folds to form a hollow tube called the neural tube. This will become your baby's brain and spinal cord.
Defects in one end (the "tail end") of the neural tube lead to spina bifida. Defects in the "head end" lead to anencephaly, when the bones of the skull do not form properly.
Folic acid prevents spina bifida. You should start taking it as soon as you find out you're pregnant (even before you get pregnant, if possible).
You at 5 weeks
This is the time of the first missed period, when most women are only just beginning to think they may be pregnant.
Find out what to expect on your NHS pregnancy journey.
Antenatal care (also called pregnancy or maternity care) is the care you get from midwives and doctors during your pregnancy to make sure you and your baby are as well as possible.
Contact your GP surgery or your preferred maternity service promptly once you know you're pregnant, so you start getting care at the right time. They'll arrange your first midwife appointment.
Starting your maternity care early in pregnancy is important if you have a health condition that may affect your pregnancy, such as heart or lung conditions, epilepsy, mental health problems, diabetes or asthma.
Your doctor or midwife will be able to advise you if you're taking medicines for your condition while you're pregnant, and provide the specialist care you and your baby need.
Do not stop taking any prescribed medicine without checking with your doctor or midwife first.
Things to think about
- You're advised to take 400 micrograms of folic acid a day while you're trying to get pregnant and until the 12th week of pregnancy.
- Stopping smoking is one of the best things you can do for your baby's health. Sign up for 28 days of free quitting advice and tips to your inbox.
- Avoid some foods in pregnancy to protect against infections.
- You can save a to-do list to keep track of things to do, such as taking folic acid and getting free dental care.
- Talk to your midwife, doctor or pharmacist before taking any medicines, or any herbal or homeopathic remedies.
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Video: Is the pregnancy test accurate?
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Media last reviewed: 5 February 2020
Media review due: 5 February 2023
Page last reviewed: 12 October 2021
Next review due: 12 October 2024
Pregnancy at week 5 | Pregnancy Birth and Baby
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Your baby
By week 5, your baby has burrowed into the wall of your uterus. It is now called an embryo and measures about 2mm from end to end. The foundations for all of the major organs are in place. The baby is inside an amniotic sac, a bag of fluid that protects it.
The cells in the baby are still dividing. In week 5, the brain and spinal column are already starting to form. The spinal cord is called the neural tube and is developing as an open groove. Your baby’s head is much larger than the rest of the body at this stage as the brain and face are developing very rapidly.
Your baby’s heart will start beating this week. The blood vessels are already starting to form and blood is circulating in the baby’s body. A string of blood vessels connects you to your baby, and this will eventually become the umbilical cord.
Your baby at 5 weeks
Length: | 2mm |
Your body
Week 5 is when most women start to wonder whether they may be pregnant. You will have missed your period, but you may be feeling like it’s just about to start. You may notice your breasts are larger and feel sore, and you may be feeling quite tired.
Some women may feel nauseous, or notice they need to go to the toilet more often than usual.
You will also be producing more human chorionic gonadotropin (hCG).
Things to remember
You can do a pregnancy test the day after you miss your period. There are many different tests available, so make sure you follow the instructions carefully.
If the pregnancy test shows you’re pregnant, it’s a good idea to see your doctor as soon as possible. They will confirm you are pregnant and advise you on how to look after yourself and your baby.
Finding out you’re pregnant can be very exciting. But for some women, pregnancy is unplanned. Whether the baby was planned or not, you may feel a range of emotions from joy to surprise to shock.
It’s important not to drink any alcohol, smoke cigarettes or take illicit drugs if you’re pregnant since these can all be very harmful for your baby.
Read next
Your pregnancy at 6 weeks
Learn about your pregnancy journey and what is happening to you and your baby.
Speak to a maternal child health nurse
Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.
Sources:
Raising Children Network (Pregnancy week-by-week), Women's and Children's Health Network (The first 3 months of pregnancy: the first trimester), Parenthub (5 weeks pregnant), Australian Journal of General Practice (Preconception care)Learn more here about the development and quality assurance of healthdirect content.
Last reviewed: August 2020
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- Pregnancy week-by-week
- Third trimester
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5-8 weeks of pregnancy
The fifth week for a baby
The fifth week of embryo development is significant for the separation of the body of the unborn child and extra-embryonic auxiliary structures - the yolk sac, amniotic bladder, chorion. The process of active formation of organs and tissues continues. At this time, the birth of all the main systems of the future organism is taking place.
At the fifth week, the size of the embryo is 1.2-1.5 mm. It is possible to see the anterior pole - the place of the future head, as well as the posterior pole - the place of the future legs. The formation of the body occurs according to the law of symmetry - a chord is laid along, which is the axis of symmetry. It is around it that the laying of future symmetrical internal organs takes place. In the future, some of them will be formed by merging the rudiments (liver, heart), and some will remain double (lungs, kidneys, etc.). nine0005
The fetus in this period is in a curved state and looks like the letter C. By the end of the fifth week, the heart begins to pulsate, which has already formed. From the middle germ layer (mesoderm) begins the formation of the pancreas, liver, lungs, thyroid gland, trachea and larynx.
On the fifth allotment, the formation of the central nervous system also begins. The cells, which were previously located flat, begin to roll up, i.e., the formation of the neural tube occurs. The viability of the fetus is largely dependent on the complete closure of the tube, so the fifth week is of great importance. Folic acid is able to contribute to the high-quality closure of the tube. Therefore, when planning a pregnancy, specialists recommend taking drugs containing this substance. Also, folic acid is needed throughout the first trimester, but its role is especially important during 5-7 weeks. Along the tube there are bulges from which the formation of the brain sections will occur. nine0005
The processes located along the neural tube are called somites and represent future muscles.
Also, the fifth week is characterized by the beginning of the formation of germ cells in the embryo - this is another important moment in his life. In future people, at the stage of early development, the rudiments of eggs and spermatozoa are already laid.
Expectant mother at the fifth week
The period of five weeks is quite early, so if changes occur in the female body, they are insignificant. At this time, the cycle delay is one week, which not every woman pays attention to. If she is aware of her situation, thoughtfulness, peace, or, conversely, high activity may appear. nine0005
Odor intolerance and nausea are likely from the fifth week. Most women are prone to early toxicosis, which manifests itself in the form of vomiting, which usually occurs in the morning. Toxicosis can be both mild and severe. The second is accompanied by incessant vomiting. Women who are faced with a severe form of toxicosis are subject to hospitalization.
A feeling of heaviness in the chest or slight pain when pressed is also a sign of early pregnancy. nine0005
Sixth week for baby
During the sixth week, the embryo grows from approximately 3 mm to 6-7 mm. At this time, the shape of the embryo is cylindrical and resembles to a certain extent the embryo of a fish. The rudiments of arms and legs appear along the body, which in the sixth week have the form of processes. The arms are formed faster than the lower extremities; by the end of the sixth week, the rudiments of the hands are formed. The legs are not yet formed at the moment and remain in the rudimentary stage. At this time, the tube must completely close, and the rudiments of the hemispheres are formed from the brain bubbles. nine0005
The heart at this stage is characterized by intensive development and active pulsation. Inside this organ, division into chambers and compartments occurs, ventricles and atria appear. If you use highly sensitive ultrasound equipment, the heartbeat of the fetus can already be caught. 100-160 beats per minute at this stage makes the heart.
Also on the sixth week, the digestive tube is formed, which ends with the formation of the large and small intestines, stomach. nine0005
The sex glands continue to develop, the ureters are formed. An important process at this stage is the formation of chorionic villi, i.e., the laying of the future placenta. The sixth week is marked by the active stage of vascular growth and the "training" of the placenta. Of course, as a separate organ, the placenta has not yet formed and does not fulfill its functions, but the first trial steps are already being taken - there is an exchange of blood between the mother and the embryo, such an exchange is the precursor of future blood circulation. nine0005
The sixth week for the expectant mother
If the cycle is delayed by two weeks, which corresponds to the sixth obstetric week, the manifestations of toxicosis may increase in a woman. Nausea often leads to vomiting. If this happens more than two or three times a day, you should contact a specialist. In the chest, vascular permeability changes due to changes in the hormonal background. Therefore, a periodic sensation of tingling may join the feeling of fullness of the glands.
A woman in the sixth week is often accompanied by irritability, drowsiness, fatigue and weakness. All of these symptoms are the result of the influence of the hormonal background, which tries to create the best conditions for the development of the child. Experts note that the severity of the course of toxicosis directly depends on the emotional state of the woman. Therefore, the expectant mother should limit physical activity, avoid stressful situations, provide positive emotions and good mood. nine0005
Women may develop new taste preferences. Undoubtedly, it is necessary to ensure the comfort of the expectant mother, but one should not forget about common sense when choosing a diet. Even if it attracts to harmful products, they should not be consumed, of course, smoking and alcohol are contraindicated. It is undesirable to use smoked meats and any products containing chemical elements. The more correct the diet, the more benefits it can bring to the unborn baby.
Special attention should be paid to the water balance. Dehydration can only aggravate toxicosis, so it is important to monitor the amount of fluid consumed. Sometimes fruits, water and juices even become the only possible food for a woman. nine0005
Seventh week for a baby
At this age, the embryo reaches a length of 8-11 mm, its weight at the seventh week is less than a gram. The head is equal in size to half the body, while the shape of the body is arched. You can see in the lower part of the pelvic end a continuation of the coccyx, which outwardly resembles a tail.
On the seventh week, the formation of the embryo occurs quite intensively. On the hands, you can already see the interdigital spaces, but there is no division into individual fingers yet. The embryo begins to develop a face, on which a nasal fossa appears. In this place, a nose is formed a little later. Also in the seventh week, the initial development of the auricles occurs. They begin to form from two elevations on the head, both jaws are formed. nine0005
The seventh week is characterized by such an important event as the formation of the circulatory system of the female body and the fetus, as well as the umbilical cord. There is uteroplacental blood flow. From now on, tissue respiration and nutrition of the fetus occur through maternal blood. The unborn child falls under the protection of the mother's body. The future placenta (chorion) not only nourishes the embryo, but also acts as a protective filter, preventing harmful microorganisms and toxins that can significantly harm the fetus. nine0005
The seventh week for the future mother
From the seventh week, the growth of the uterus begins in a woman, this can be determined by a specialist during a gynecological examination. At this stage, many expectant mothers have an increase in the abdomen, which is one of the main signs of pregnancy. The growth of the uterus and the size of the embryo cannot cause an increase in the abdomen. This is due to the action of progesterone, which leads to lethargy of the intestinal loops, as well as a decrease in the tone of the anterior abdominal wall. Bloating occurs, which is the cause of visible changes in the abdomen. nine0005
Increased urination is a consequence of the fact that the total volume of blood in the female body increases. Such a change will accompany the expectant mother throughout the pregnancy and will especially manifest itself in the last trimester. If pain occurs during urination, then there is a reason for a visit to the doctor, since this is not considered the norm. Changes in bowel function are possible, constipation and diarrhea can occur with equal probability. The reasons may be a change in the usual diet or hormonal levels. Since regular daily stools ensure the timely removal of toxins from the body of the expectant mother, it must be carefully monitored. If you have problems with bowel movements, you should consult a specialist. nine0005
Eighth week for baby
The embryo is 15-20 mm long by the beginning of the eighth week and 40 mm by the end of it. The mass of the embryo is five grams. After the eighth week, the embryonic period ends and the fetal period begins. After eight weeks, experts no longer use the term embryo, the unborn child is called the fetus until it is born. The main features of the eighth week are the intensive development and modification of the embryo. There is a straightening of the body, and it is increasingly divided into segments - limbs, head and torso. nine0005
At this stage, the nervous system is actively developing. Also on the eighth week, the brain is divided into sections, the hemispheres are more clearly outlined, convolutions are formed.
The face of the unborn child becomes more prominent, ears, nostrils, eyes are formed. By the end of the eighth week, the upper lip is fully connected, and the face looks quite distinctly formed.
The process of ossification of the skull, arms and legs belongs to the features of this period. Bones harden. The formation of the fingers occurs, and the large one becomes isolated and opposed to the palm. Large joints (elbows and knees) are formed. nine0005
Brain structures, which are responsible for muscle tone, and the muscular system itself are also being actively formed. This allows the embryo to perform a variety of movements. The development of the digestive tract is almost completed by the end of this week. The intestines and stomach are supplied with nerve endings, which in the future will be able to provide motor functions of the gastrointestinal tract, the cavities of the kidneys, heart, bladder and ureters are formed.
The vascular system develops in the future placenta. The chorionic villi penetrate deeply into the wall of the uterus. Utero-placental circulation becomes full. The complex supply of the growing fetus is provided by the vessels of the umbilical cord, through which it receives blood enriched with oxygen and a variety of nutrients. Also, through these vessels, metabolic products and carbon dioxide are removed. nine0005
The eighth week for the expectant mother
The eighth week does not bring significant changes to the woman's body. All manifestations of toxicosis do not change their character, but are already much easier to bear. This is due to the fact that by this time pregnant women get used to their condition and find factors that facilitate it and create comfort. These can be certain foods, good sleep, one or another diet, walks, etc.
In this material, the gestational age is indicated as obstetric, that is, it is calculated from the first day of the preceding pregnancy menstruation. nine0005
5th week of pregnancy what happens to the fetus
This is a period of rapid growth of the embryo. At the fifth obstetric week, the heart of the crumbs already begins to beat, and organs and tissues are also differentiated.
What happens to the child?
The fetus is not yet quite like a small child. Its weight is only one gram, and its height is 1.5-2 mm. Nevertheless, important changes are taking place in this tiny organism, internal organs are intensively formed.
- The embryo already has the rudiments of limbs and even fingers, the cochlea of the inner ear, eyes and mouth are formed. At this stage, cells begin to form that are responsible for the sex of the child. nine0088
- The spine and internal organs such as the liver, intestines, pancreas are intensively formed, the digestive and urinary systems are taking shape.
- The cardiovascular system develops, the first blood vessels appear. By the middle of the fifth week, the tiny heart is beating at about 100 beats per minute. Over time, contractions will reach 180 beats.
- The development of the nervous system begins, tissues of the spine and spinal cord appear. nine0088
At this time, the placenta is actively developing - one of the most important and unique organs that exists only during pregnancy. The placenta connects the mother and the unborn child, providing the latter with all the necessary nutrients. Such a close relationship between mother and baby through the placenta is a reason to reconsider your work and nutrition regime, to give up bad habits.
Do not forget that the fifth obstetric week coincides with the third embryonic week, that is, the real age of the baby is two weeks less. nine0005
What are the changes in the woman's condition in the fifth week?
A woman's pregnancy will be indicated by the absence of menstruation, as well as new symptoms and sensations.
- Signs such as drowsiness or insomnia, mood swings, fatigue, tearfulness, taste changes, increased sense of smell, if they were before, persist.
- In addition to engorgement and increased sensitivity of the mammary glands, pigmentation of the nipples and a strip down from the navel may appear. nine0088
- At this time, the first signs of toxicosis are likely, so avoid the factors provoking it: strong odors, fatty and too specific food. Add foods rich in vitamin B6 to your diet.
- The urge to urinate is usually more frequent.
- Always watch the nature of your sensations in the lower abdomen. If the pain is minor and short-lived, then do not worry. If they intensify or are accompanied by spotting, cause you discomfort, contact your doctor immediately. nine0088
Do not forget that the absence of the above symptoms is also considered the norm, because the size of the baby is still very small.
If there is nothing else that bothers you, then most likely the pregnancy is going well.
If any of the above symptoms are present and no menstruation occurs, a pregnancy test is negative, it is recommended to repeat the pregnancy test after 3-5 days.