Pregnancy and baby

You and your baby at 0-8 weeks pregnant

Should I take supplements during my pregnancy?

Media last reviewed: 20/03/2014

Next review due: 20/03/2016

Your baby's early development

Weeks 1-3

Your weeks of pregnancy are dated from the first day of your last period. This means that in the first two weeks or so, you aren't actually pregnant – your body will be preparing for ovulation as usual. You ovulate (release an egg) around two weeks after the first day of your period (depending on the length of your menstrual cycle).

During the third week after the first day of your last period, your fertilised egg moves along the fallopian tube towards the womb. The egg begins as a single cell, which divides again and again. By the time the egg reaches the womb, it has become a mass of more than 100 cells, called an embryo. Once in the womb, the embryo burrows into the lining of the womb. This is called implantation.

Week 4

In weeks four to five of early pregnancy, the embryo grows and develops within the lining of the womb. The outer cells reach out to form links with the mother’s blood supply. The inner cells form into two, and then later, into three layers. Each of these layers will grow to be different parts of the baby’s body.

The inner layer, called the endoderm, becomes the breathing and digestive systems, including the lungs, stomach, gut, and bladder. The middle layer, called the mesoderm, becomes the heart, blood vessels, muscles, and bones. The outer layer, called the ectoderm, becomes the brain and nervous system, the eye lenses, tooth enamel, skin and nails.

In these early weeks of pregnancy the embryo is attached to a tiny yolk sac which provides nourishment. A few weeks later, the placenta will be fully formed and will take over the transfer of nutrients to the embryo.

The embryo is surrounded by fluid inside the amniotic sac. It's the outer layer of this sac that develops into the placenta. Cells from the placenta grow deep into the wall of the womb, establishing a rich blood supply. This ensures the baby receives all the oxygen and nutrients it needs.

Week 5

The fifth week of pregnancy is the time of the first missed period, when most women are only just beginning to think they may be pregnant. Yet already the baby’s nervous system is developing, and the foundations for its major organs are in place. At this stage the embryo is around 2mm long.

As the ectoderm develops, a groove forms and the layer of cells folds to form a hollow tube called the neural tube. This will become the baby's brain and spinal cord. Defects in the "tail end" of the neural tube lead to spina bifida, while defects in the "head end" lead to anencephaly (when the bones of the skull do not form properly).

At the same time, the heart is forming as a simple tube-like structure. The baby already has some of its own blood vessels and blood begins to circulate. A string of these blood vessels connects the baby and mother and will become the umbilical cord.

Week 6

By the time you are six to seven weeks pregnant, there is a large bulge where the heart is and a bump at the head end of the neural tube. This bump will become the brain and head. The embryo is curved and has a tail – it looks a bit like a small tadpole.

The heart can sometimes be seen beating on a vaginal ultrasound scan at this stage.

The developing arms and legs become visible as small swellings (limb buds). Little dimples on the side of the head will become the ears, and there are thickenings where the eyes will be. By now the embryo is covered with a thin layer of see-through skin.

Week 7

By seven weeks, the embryo has grown to about 10mm long from head to bottom. This measurement is called the "crown-rump length". The brain is growing rapidly and this results in the the head growing faster than the rest of the body.

The embryo has a large forehead, and the eyes and ears continue to develop. The inner ear starts to develop, but the outer ear on the side of the head won't appear for a couple more weeks.

The limb buds start to form cartilage, which will develop into the bones of the legs and arms. The arm buds get longer and the ends flatten out – these will become the hands.

Nerve cells continue to multiply and develop as the nervous system (the brain and spinal cord) starts to take shape.

Week 8

By the time you're eight weeks pregnant, the baby is called a foetus, which means 'offspring'.

The legs are lengthening and forming cartilage too. The different parts of the leg aren't properly distinct yet – it will be a bit longer before the knees, ankles, thighs, and toes develop.

The foetus is still inside its amniotic sac, and the placenta is continuing to develop, forming structures called chorionic villi that help attach the placenta to the wall of the womb. At this stage, the foetus still gets its nourishment from the yolk sac.

Your body in early pregnancy

Conception usually takes place about two weeks after your last period, around the time that you ovulate (release an egg). In the first four weeks of pregnancy you probably won’t notice any symptoms. The first thing most women notice is that their period doesn’t arrive. Find out about the signs and symptoms of pregnancy.

By the time you are eight weeks pregnant, you will probably have missed your second period. However, some women experience a little bleeding during the early weeks of pregnancy. Always mention any bleeding in pregnancy to your midwife or GP, particularly if it continues and you get stomach pain.

Your womb has grown to the size of a lemon by the time you are around seven or eight weeks pregnant. You’re probably feeling tired. Your breasts might feel sore and enlarged, and you are probably needing to pass urine more often than usual.

Some pregnant women start to feel sick or tired, or have other minor physical problems for a few weeks around this time. Most women stop having feelings of nausea (morning sickness) and start to feel better by the time they are around 14 weeks pregnant.

What to do if you're pregnant

Finding out you’re pregnant

The most reliable way of finding out whether you’re pregnant is to take a pregnancy test. Once you think you could be pregnant, it’s important to get in touch with a midwife or doctor to start your antenatal (pregnancy) care.

Help and advice for teenagers

Discovering you’re pregnant can be tough, but there is help out there.

Common pregnancy problems

From morning sickness to vaginal bleeding, find out how to cope with the minor and more serious symptoms that can occur in pregnancy.

Your feelings and relationships

Pregnancy is a time of physical and emotional changes that can affect your relationships, so get as much information and advice as you can to help you cope.

Antenatal care

The best way to make sure both you and your baby stay healthy is to make sure you get all the care available to you during pregnancy. This includes scans and checks, screening, and free dental care.  

You can save a to-do list online to keep track of things to do, such as taking folic acid and getting free dental care.

Pregnancy week by week

Find out what's happening to you and your baby at:

9, 10, 11, 12 weeks pregnant

13, 14, 15, 16 weeks pregnant

17, 18, 19, 20 weeks pregnant

21, 22, 23, 24 weeks pregnant

25, 26, 27, 28 weeks pregnant

29, 30, 31, 32 weeks pregnant

33, 34, 35, 36 weeks pregnant

37, 38, 39, 40 weeks pregnant

Over 40 weeks pregnant


Page last reviewed: 09/02/2015

Next review due: 09/02/2017


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The 11 comments posted are personal views. Any information they give has not been checked and may not be accurate.

daynighthealthcare said on 26 May 2015

There are different stages of pregnancy and each stage there is different development in the baby happen. And during each stage there is must required special care for pregnant lady and that pregnant lady must have to do some changes in their daily routing life like

Avoid during pregnancy like junk food, quit smoking and alcohol, cut down coffee, sea foods, hot baths and saunas.

Eat during pregnancy like Eat healthy foods, Exercise regularly, Take rest, be positive, and Drink plenty of water.

<b><a href="">Precautions during early pregnancy</a></b>

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Tonijay89 said on 27 April 2014

I just found out I'm pregnant when I looked online it says around 5 weeks, I've had a miscarriage in the past and have been getting some spotting and stomach cramps and a feeling of butterflies just trying to find out if this is all normal?

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Chrissy83 said on 03 December 2013

@ user 793838
I was just wondering if everything came out OK for you? I hope so!!!

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Chrissy83 said on 03 December 2013

Hello everyone, I found out that I was pregnant 3 weeks ago this would be my 5th pregnancy with 2 live births. I have had 8 positive hpt and this morning I took one and it told me that it was negative. After I found out I was pregnant I started to have pains in my belly and then it stopped. A few days later I started to bleed, after 4 days of bleeding I was fine and took some more hpt and they all came back positive until this morning. I have been spotting again, but after the test this afternoon I started to feel movement in my pelvic region like butterflies. Is there still a possibility that I really am still pregnant? I have an appointment on the 12thand i really want to go but at the same time I am afraid that they are going to tell me that I yet lost another baby! If so that will be the 4th miscarriage in a 3 year span. Is there something wrong with me?

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themist23 said on 20 November 2013

hello i have just found out I'm pregnant yestaday I'm not shore how fare I am as I had an odd period on the 20th of October I was a week early and it onley lasted 2 days normal flow and nuthink this mouth that's why I did a test

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User793838 said on 08 August 2013

Hello I just found out I'm 5 weeks pregnant! The day after I found out I started passing Brown discharge and getting period like pains! I went to my doctor who arranged for me to have my hcg levels tested, they come back o.k. But I'm still receiving pain and it's always in my lower back - I've not had any sickness but my breasts are kinda sore! Is the pain normal?? Xx

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Charley31 said on 03 August 2013

Hi there, I took a test lat week that came back positive :) I took another one just to make sure and it has also come back positive ( clear blue digital, it says I'm 1-2 weeks) I'm really excited but I haven't seen my gp yet. Today I had a brown discharge in my underwear but there was nothing when I went to the toilet, then later on this evening the brown discharge was there again but more than earlier and it was visible when I wiped. I'm panicking because I have no idea if this is normal or of I should worry. I'm in no pain and haven't had any cramps atall just the discharge. Any advise would be much appreciated.

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Fudge89 said on 20 July 2013

Hello all.
I'm very excited as I am 8 weeks pregnant and have just made my first appointment with my midwife. This is mine and my husbands first baby and we couldn't be happier. I just wanted to share my joy and excitement with all of you and good luck with the future.

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Anonymous said on 09 June 2013

Does it really matter that I am living on third floor flat and we do not have lift, I am four weeks pregnant, should I need to change property or it will be ok?

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HappyCoral said on 19 May 2013

Hi:) I have had a positive test for pregnancy and the G.p estimated this to be 5 weeks-which will be 6 weeks now-it took a while to sink in and also I am still ill with a viral type thing. It apperas to be turning into a chest infection-my husband has a bad chest at the minute and is on antibiotics. I have severe asthma and try to catch these things quickly due to this.

I have lots of questions for the midwife and have made a list of 11 so far on my mobile. My main concerns are-If my virus becomes a bad respiratory infection can I have the medication I need without causing undue risk to the development of what I really hope to be a healthy um-pre feutus stage.

I am scared-this is my first. I read something about a person having a scan and atho they had all the signs-there was nothing that could be seen. I am anxious about this-also my OBS is worse as I cannot take the medication I usually would for this.

Good grief I feel sorry for the midwife that has to speak to me at the minute I'll be bowling her over with questions and concerns-but I suppose they are used to that bless them.

Anyway-panicking aside-here is to a happy and healthy as possible time for us all and best wishes and good luck to everyone on this forumxxx

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sarahrhodes said on 15 March 2013

I have just discovered I'm 5-6wks so very early on. My pants have always dug in a bit when I sit down as I'm a bit overweight, but someone said this could damage my embryo? Is it true? Do I need stretchy pants now? Help

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