First trimester: weeks 1 to 12

You're pregnant: congratulations! The first weeks of your pregnancy are a vital time as your body gets busy building a baby. How exciting!

Weeks 1-12 infographic

First trimester: key stages

The first trimester begins on the first day of your last period and lasts until the end of week 12. This means that by the time you know for sure you're pregnant, you might already be five or six weeks pregnant!

A lot happens during these first three months. The fertilised egg rapidly divides into layers of cells and implants in the wall of your womb where it carries on growing. These layers of cells become an embryo, which is what the baby is called at this stage.

During this trimester, your baby grows faster than at any other time. By six weeks, a heartbeat can usually be heard and by the end of week 12, your baby's bones, muscles and all the organs of the body have formed. At this point, your baby looks like a tiny human being and is now called a fetus. He or she will even be practising swallowing!

When am I due?

Find out your due date using our due date calculator!

When will I see a midwife?

Your first midwife appointment (also known as antenatal appointment) is the 'booking' appointment. This usually happens between week 8 and 10 of your pregnancy. Find out how to register with a midwife and when your appointments will be here.

Keeping your baby safe

There are some things that you can do during pregnancy that have an effect on your baby. Find out about them by clicking the link below.

Find the complete list of pregnancy dos and don'ts (and reasons why) here

Not sure whether you are pregnant?

Find out about the symptoms that mean you may be pregnant here.

Your physical and mental health in pregnancy

We also have lots of useful tips for coping with everyday pregnancy niggles. It’s common for women to experience symptoms such as morning sickness, cramp and indigestion during the first trimester. 

Don't forget that your mental health is just as important as your physical health. It's normal to feel some anxiety and stress but it shouldn't be ongoing. If what you’re feeling isn’t normal for you, talk to your GP or midwife about it. They are there to help. 

Exercise, such as yoga, has been shown to reduce anxiety and is a great way to stay active during your pregnancy, too.

Read more about mental wellbeing in pregnancy

Read more about diabetes and pregnancy

Read more about pregnancy with a high BMI

Read more about exercise and pregnancy

Read about the symptoms to look out for in pregnancy

Track your baby's development

Sign up to a free pregnancy email from our midwives to track your baby's development and give you reminders of all you need to know through the nine months of pregnancy. Click here to sign up.


Find out more about the first trimester


NHS Choices. Your pregnancy week by week (Page last reviewed: 28/02/2017 Next review due: 28/02/2020)

Macdonald S, Magill-Cuerden J (2012) Mayes’ Midwifery, 14th edition, London, Ballière Tindall

NICE (2008) Antenatal care for uncomplicated pregnancies, NICE Clinical Guidelines 62. National Institute for Health and Care Excellence

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Last reviewed on June 28th, 2018. Next review date June 28th, 2021.

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Please note that these comments are monitored but not answered by Tommy’s. Please call your GP or maternity unit if you have concerns about your health or your baby’s health.
  • By Krithika (not verified) on 17 Nov 2017 - 05:54

    Hi, got my last period on sept 22, lasted til 4 days. I have pcod but I have been getting period regularly at least for past 4 months , since may. I didn’t get period after sept. Did Multiple home test and one blood test. All were negative. Hcg < 1 on October mid. I have nausea, motion sickness, cramp in lower abdomen, frequent urination, lower back pain, tiredness. Had spotted twice , two week before , just two drops. After that had intercourse, followed by white discharge for two continuous days. It’s been 56 days I didn get my period yet. Could I b pregnant , with hcg < 1 ? I heard hcg may not b present in every pregnant lady. Is that true.

  • By Midwife @Tommys on 17 Nov 2017 - 11:53

    Hi, HCG is a pregnancy hormone which rises quickly during pregnancy, and happens for every pregnant woman. A level of less than 5 is negative for a pregnancy, a level above 5 shows a pregnancy. If you are continuing to have negative pregnancy tests but still having the symptoms you describe then do go see your GP to be reviewed. Take care, Tommy's midwives

  • By Midwife @Tommys on 17 Nov 2017 - 11:55

    Hi, HCG is a pregnancy hormone which rises quickly during pregnancy, and happens for every pregnant woman. A level of less than 5 is negative for a pregnancy, a level above 5 shows a pregnancy. If you are continuing to have negative pregnancy tests but still having the symptoms you describe then do go see your GP to be reviewed. Take care, Tommy's midwives

  • By Krithiks (not verified) on 17 Nov 2017 - 18:20

    Thank u for the quick reply. This site is one of the few sites where ladies like me get very quick supportive reply. Thank u

  • By Midwife @Tommys on 20 Nov 2017 - 09:13

    Hi Krithiks, you're very welcome! We are always happy to help! :)

  • By Anonymous (not verified) on 30 Nov 2017 - 02:30

    I am in the same boat as you! I haven’t gotten my period since September 15th and all my tests are negative. Did you find out if you were pregnant or not?

  • By Meg (not verified) on 16 Nov 2017 - 07:02

    Hello, this is my 3rd pregnancy. My last ended in a miscarriage at 7 weeks. I am currently just 5 weeks pregnant. Early this morning whilst lying in bed I coughed and this sent a shooting pain in my lower abdomen. Is this muscular? It lasted a new seconds, but still feels a bit sensitive hours later. Thanks

  • By Midwife @Tommys on 16 Nov 2017 - 09:25

    Hi Meg
    If the pain was very severe and you have been left with that sensation still, then it might be worth contacting your local early pregnancy assessment unit or GP for assessment. If you have any bleeding or cramps/abdominal pain in pregnancy, at any gestation, then we would always suggest that you are reviewed by a doctor/GP. Please take good care of yourself.

  • By Meg (not verified) on 16 Nov 2017 - 13:58

    Thank you for your response. I spoke to my doctor and she thinks it sounds muscular as it was a reaction to the cough. Fingers crossed x

  • By Anonymous (not verified) on 14 Nov 2017 - 19:50

    Please help.
    I home pregnancy test four times and it all show positive.
    But my doc said that I need to do blood test to confirm, please will the result be positive again, because am so happy.
    Pls reply me

  • By Midwife @Tommys on 15 Nov 2017 - 12:39

    Hi, Thank You for your comment.

    If you have done 4 pregnancy tests and they have all come back positive then this is a positive sign that you are pregnant. The blood test done by the GP will test for the HCG pregnancy hormone in the blood which is also picked up on a urine pregnancy test. It would be highly unlikely that this test would come back negative as this test is more sensitive on a blood test then in the urine. As you have had 4 positive pregnancy tests then your GP would expect to see a positive blood test, however, this can only be confirmed 100% by getting a positive result from this test. Hope this helps, take care, Tommy's Midwives x

  • By Anonymous (not verified) on 12 Nov 2017 - 07:40

    Hi, I am 12 weeks 3 days pregnant and have my first scan on Tuesday. I have had no symptoms during the first trimester except for being a little more tired and hungry than usual (no nausea, sickness, sore breasts etc). Is this normal?? I have had no severe cramps or bleeding, although I did have one tiny pink spot when wiping at 6 weeks 1 day. I am so nervous that something will be wrong at my scan as I just don't feel pregnant! Is this normal?? Thankyou.

  • By Midwife @Tommys on 13 Nov 2017 - 14:35

    Hello. This is a very common concern from women before they have their first scan. While I cannot guarantee that all is well, there is no reason to be concerned. Early pregnancy symptoms vary from one woman to the next and an absence of pregnancy ailments is nothing to worry about. For you, being tired and hungry is your pregnancy symptom. I hope all goes well tomorrow, Let us know x

  • By Anonymous (not verified) on 11 Nov 2017 - 05:31

    Hi i had my periods 9th October . We had intercouse on 22nd . How far along am i. Between then i had used drugs to hasten my periods as i had exams and i didn't want period stress, can my baby be affected by the drugs i used?

  • By Midwife @Tommys on 13 Nov 2017 - 14:23

    You would be approx. 5 weeks today. If you have a positive pregnancy test you should stop taking the medication that you have and arrange to see your doctor as soon as you can.

  • By Anonymous (not verified) on 9 Nov 2017 - 16:50

    Hi im 9weeka pregnant on 3days ago i felt the pain on bottom of my right stomach it's killing me, what can i do to save my pregnancy?

  • By Midwife @Tommys on 10 Nov 2017 - 09:52

    Sorry to hear that you are experiencing pain, from your description it is difficult to say exactly what is causing this pain and if it is still on going. If the pain has stopped and you have no other concerns then just monitor how you are feeling. If the pain is on going or returns then you may need to be reviewed. If you have not yet had a scan and you have on going pain on one side of your stomach low down then you need to see your GP or midwife to rule out an ectopic pregnancy. Otherwise it can be the start of some ligament pain as the baby is growing, or sometimes trapped wind, which is very common in pregnancy. If you also have any bleeding or any other concerns then you will need to see your GP or midwife.

  • By Adex (not verified) on 9 Nov 2017 - 14:03

    Hi! I am 13wks pregnant and this is my first pregnancy but sometimes do mistakenly sleep on my tummy and sometime on my back so am afriad if this is not going to have a physical or health challenge on my baby. Pls am curious to hear from you. Tanx

  • By Midwife @Tommys on 9 Nov 2017 - 14:46

    Thank you for your comment & congratulations on your pregnancy. I hope by now you have had your 1st scan, midwife booking appointment and started your antenatal care.
    Research has shown that it is better for the baby if you go to sleep lying on your side. This is especially important after 28 weeks of pregnancy-I have attached a link that you may find helpful-
    At your early stage of pregnancy, try to go to sleep lying on your side and then if you wake up and find you have moved onto your back or stomach then just turn onto your side to go back to sleep. (Whilst you are asleep your body will naturally move into different positions which you cannot control while asleep. This is not harmful to your baby)
    Hope this helps

  • By Anonymous (not verified) on 10 Nov 2017 - 03:49

    Thanks. Already had a scan and also started ante natal care, thanks for the quickly response.

  • By Dolly (not verified) on 30 Oct 2017 - 15:50

    Plz I had preterm delivery in my last pregnancy. My water broke at 5months and now am pregnant again so am afraid if same thing will happen again or I should go for cerlage. Plz help me out

  • By Midwife @Tommys on 31 Oct 2017 - 09:24

    Hi Dolly
    I can understand why you are concerned about having another premature birth with this baby. It would be sensible for you to get booked in by your midwife and be referred to the obstetric team as soon as possible so that they can make an early plan of care for you in this pregnancy. The obstetric team at your first consultation can go through your obstetric and medical history and try to understand what might have caused your babies premature birth in your last pregnancy. There are many reasons why this might have happened. Please take good care of yourself and get in touch if you need any further support. Sophie, Tommy's Midwife

  • By Anonymous (not verified) on 30 Oct 2017 - 15:36

    Plz I had preterm delivery in my last pregnancy. My water broke at 5months and now am pregnant again so am afraid if same thing will happen again or I should go for cerlage. Plz help me out

  • By Midwife @Tommys on 30 Oct 2017 - 16:42

    Hi. Can you discuss this with your GP or with a midwife if you are to see one soon and arrange to be seen by the obstetric consultant. He or she will be able to access your notes from your previous pregnancy and make a plan of care based on your needs. They will be very happy to discuss the pros and cons of any procedure or to advise you if a cerclage is not recommended and to explain why. Best of luck

  • By Anonymous (not verified) on 28 Oct 2017 - 14:15

    hi iam pregnant 2 week and 3 day I have suffering leg pain or back pain and little bit of discharge its that ok I have 4 year old son and 1 miss carriage what can I do to save my pregnancy plz

  • By Midwife @Tommys on 30 Oct 2017 - 11:25

    Hi, Back and leg pain is not usually linked to a pregnancy at this stage and advice is to keep as active as possible. An increase in discharge is normal in pregnancy and is usually thin, milky white and mild smelling. If you pass any blood or the discharge is foul smelling you should contact your doctor or midwife. Best wishes x

  • By Anonymous (not verified) on 12 Oct 2017 - 17:57

    Hi..I had intercourse last night ...only once. with my wife during her 8 weeks pregnancy... Then I knew about to avoid sex during I am much worried about the safety of my child....plz assure me about this this time I won't repeat it..

  • By Midwife @Tommys on 16 Oct 2017 - 10:37

    Hi there.
    Intercourse is usually deemed to be safe during pregnancy - unless your midwife or doctor has told you specifically that it is best avoided due to certain medical conditions. If this is not the case, then it is normal to want to keep an active sex life during pregnancy if you and your wife are both consenting to this.
    The baby is very safely protected inside the uterus, surrounded by amniotic fluid, with the cervix keeping baby safely inside.
    If you have any further questions, please do get in touch

  • By Anonymous (not verified) on 9 Oct 2017 - 14:28

    Me and my fiance are a same sex couple and we did an at home insemination.. We have 4 negatives and one positive. We have had two miscarriages. Now we think we're pregnant forsure but she's having heavy bleeding but no signs of miscarriage. Help?!

  • By Midwife @Tommys on 11 Oct 2017 - 13:54

    I am sorry but I don't really understand your situation. Has she had a positive pregnancy test? I am concerned that if she is bleeding heavily this may be a sign of miscarriage. Please take care x

  • By Anonymous (not verified) on 8 Oct 2017 - 10:17

    I have tried having sex on my danger days for some months now to conceive but no positive result.what could be wrong. I have been on folic acid since I made up my mind to conceive.

  • By Midwife @Tommys on 9 Oct 2017 - 16:38

    Hi Unfortunately it is not uncommon for it to take a year or more to conceive. Check out our Top tips for conception and ensure that you are maintaining a healthy weight and lifestyle to give you the best chance.

  • By Emma (not verified) on 19 Oct 2017 - 22:36

    Keep going I had polycystic ovary syndrome and it took me 4 1/2 years I have all the nutrients and pills and diets and water just keep trying and don't give up :)

  • By Anonymous (not verified) on 20 Sep 2017 - 12:46

    Hi I am 7 weeks plus 2 days pregnant and I have been having a browny/orange discharge for the last 5 days. No cramps, or bright red blood/spotting but just an odd colour discharge when I wipe after going to the toilet. I have a history of group b-strep in previous pregnancies and was diagnosed with pcos earlier in the year. Should I be worried? Xx

  • By Midwife @Tommys on 20 Sep 2017 - 14:49

    Hi there,
    spotting at any gestation of pregnancy, with or without the presence of abdo pain, should ideally be reviewed at your local early pregnancy assessment unit. It is likely that all will be well, but it is always best to get a little check up- mostly to put your mind at ease. The color of the discharge is also a little unusual, so that would be another reason for you to go in, they may want to take a low vaginal swab culture to see if anything grows in relation to your history. Please take good care of yourself and feel free to contact us again by email, phone or website and we will be happy to help! All the best !

  • By ummi ubaidah (not verified) on 19 Sep 2017 - 08:54

    my last period on 2/8/2017..
    i recently did pregnancy test and it is positive. so what should i do because this is my first pregnancy.. thanks in advance... what supplement i should consume???

  • By Midwife @Tommys on 19 Sep 2017 - 12:25

    Thanks for posting. It would be a good idea to contact your GP so that you can be referred for an ultrasound scan in about a month's time ( 12 weeks) and you will also need to have a booking appointment with the midwife.
    You ask about supplements, go out and get some Folic Acid (400 mcg daily) today this is really important for your baby's development until 13 weeks.
    Vitamin D ( (10 mcg daily) is also a supplement to take throughout pregnancy and during breastfeeding.
    Please see your dentist during pregnancy as pregnancy hormones can affect your gums. Prescriptions and dental treatment are free in pregnancy and until your baby is a year old.
    I hope this helps please get in contact any time if you have more questions.
    Best wishes
    Anna-Tommy's Midwives

  • By Tiffany (not verified) on 10 Sep 2017 - 20:40

    Yay after 3months of trying im pregnant I took two tests one saying 2-3weeks pregnant :) so do I look at the 4-5weeks progress ? As my last period?

  • By Midwife @Tommys on 11 Sep 2017 - 15:43

    Congratulations on your pregnancy news! It sounds as if you in the very early stages of pregnancy so have a look at 4 weeks+ information pages to start finding about all the exciting changes occurring
    You can also find out how weeks pregnant you by using due date calculator

  • By Christiana (not verified) on 5 Sep 2017 - 12:00

    I am 13weeks pregnant but since i enter the 12 weeks am having severe headache and my stomachache.i have been paracetamol but is not working.pls what should i do

  • By Midwife @Tommys on 5 Sep 2017 - 14:49

    Hi Christiana,
    I'm sorry that you are feeling so unwell in your pregnancy. Have you had a scan recently? It is difficult to know if the stomach ache is only pregnancy related or if you have another issue going on? If you have abdominal pain or bleeding you should be seen by the early pregnancy unit but this may need to be arranged through your GP.
    The headaches are common in pregnancy this is due to hormonal changes. In pregnancy you may also suffer from migraines.
    Ensure that you are well hydrated and see you GP to see what other options are available if the paracetamol is not helping you.
    I hope this helps. Please get in touch any time over your pregnancy too.
    Anna-Tommy's Midwives

  • By Midwife @Tommys on 29 Aug 2017 - 13:03

    Hi, thank you for your post. I am not sure if you were needing medication for pain or sickness?
    It is safe to take paracetamol for pain in pregnancy but if you need something for the nausea and vomiting please see your doctor and check out this brilliant charity for other practical advice
    Your pharmacist is also a great resource in pregnancy to let you know what is safe and what to avoid medication wise.
    I also find this website excellent for more detailed information about medicines in pregnancy
    Best wishes
    Tommy's Midwives

  • By MissD (not verified) on 28 Aug 2017 - 07:22

    I'm in a long distance relationship, so we do not get to be intimate often. My first day of last period was 6/18, and didn't have sex until 7/28 when I went to visit. Going by general calculation I'm over 10 weeks, but that would be impossible since we were only intimate 4 weeks ago. How far along am I really at? How do I calculate? Thank you!

  • By Midwife @Tommys on 30 Aug 2017 - 11:17

    Hi Miss D
    Using the link below, please enter the date of the first day of your last menstrual period, your average length of cycle - and this will calculate your current gestation, as well as your estimated due date for birth. Nothing is 100% accurate, an Ultrasound scan will then give you a far more accurate date based upon the measurements of the fetus.
    Congratulations! Please feel free to contact us again if you need further advice.

  • By AndRust (not verified) on 26 Aug 2017 - 23:28

    Hello, I am 18, I am trying to seek help, because I am not sure what to do and what is happening to me. It might be irrelevant to the topic, but I dunno where to go, where to ask for advice. I have never missed a period and it should have occured on 16th August until 20th August but did never show up. I had light cramps and bloated tummy though, but no bleeding. Thought I might be pregnant, though test showed negative (took it 6 days after conceiving). Today on august 26th I had a moderate bleeding, it has been gooey and light pink/brown and now is more bright red and sticky liquid form. Is it just my period being late or is it normal if I am pregnant or am I having a miscarriage?
    Thank you.

  • By Midwife @Tommys on 30 Aug 2017 - 11:12

    Hi AndRust.
    It is really very difficult to know. If you had unprotected sex at any time, then it might be possible for you to be pregnant- however, the fact that you have had a negative test means that it is unlikely that you were ever pregnant. Sometimes periods can be irregular and so the bleeding can be different to normal. It might be sensible to visit your GP, so that they can take a full history from you, repeat another pregnancy test and refer you on to a gynecology appointment if they are concerned by your history. They have full access to your medical records etc, so they are best placed to know if this is simply an odd period, a one off, or this is something that needs further investigation. It is very unlikely to be of cause for concern- so please try not to worry. Get yourself a GP appointment, and feel free to contact us if you need further advice. Look after yourself.

  • By Alex (not verified) on 13 Oct 2017 - 03:03

    Hi my last menstrual period is september 13,2107, this month of october i felt so dizzy light headed , i have severe back pain also and a mild heartburn last two days .. tell me is there a possible to become pregnant?

  • By Midwife @Tommys on 16 Oct 2017 - 12:20

    Hi Alex, if you have had unprotected intercourse then it might be possible. Feeling dizzy, light headed, having back pain and heartburn can be associated with pregnancy symptoms, but these can also be attributed to many other things too such as a virus or common cold. It might be sensible to do a pregnancy test if there is any doubt for you about this.
    Please do go to see your GP if you are still feeling unwell over the next week if your symptoms persist, especially if you have a positive pregnancy test.

  • By vivi (not verified) on 25 Aug 2017 - 20:29

    let me start by saying thanks for this forum. am 7weeks pregnant and am feeling seek, the worst of it is that it comes so bad in the evenings. I've visited the hospital and the doctor conducted both MP and widal tests but saw nothing, is it advisable to take pain relief tablets, if yes which one? thanks ma.

  • By Anonymous (not verified) on 24 Aug 2017 - 22:19

    Hi I've just found out I'm pregnant, then bled the following day but had nothing since, I went for an internal but they couldn't see anything and now I have to go back for blood tests , they said it could be an early pregnancy but Its got me chewed too bits as I thought I was further on.

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