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 Aquarius (not verified) on 30 Jan 2018 - 18:57

      I had my period last December 26.I always have regular period. Now, it's delayed for 4-5 days. I was bothered because I had loose bowel movement for 4 days, my breasts were tender and sensitive, I had migraine (which normall happens a day before my period). So i thought, i would have red day then but it didnt. ldid PT a couple of days ago, midday, and it was positive.I took a second one, and it was blurry. Today, i did the test again, anf it was blurry. Pls advise whether i am pregnant or not. I am feeling the signs for my period, but it's not happening. Thank you.

    • By Midwife @Tommys on 31 Jan 2018 - 11:41

      Hi Aquarius.
      It is difficult to say. I would suggest that you go to your GP surgery to have a test done there. If you have had unprotected sex, then it may be possible. But it would make sense to go to your GP to be 100% sure either way so that a scan can be arranged if it is positive to date the pregnancy. Please feel free to call us if you wish to discuss this further.
      Sophie,Tommy's Midwife

    • By Aquarius (not verified) on 6 Feb 2018 - 19:59

      Thank you for your advice. It's confirmed that I am pregnant at 37.I am bearing my 2nd child.
      Please enlighten me if it is safe to workout during the first trimester? What are the do's and dont's? I have been hitting the gym for a year now. Await for your advice. Thanks.

    • By Midwife @Tommys on 7 Feb 2018 - 12:03

      Hi Aquarius
      It sounds as if you are a fit woman, and there is no need to stop exercising suddenly now that you have found out that you are pregnant unless you are at very high risk during your pregnancies. It might be a good idea to inform your gym instructor that you are pregnant so that they can tailor your class/exercise to you during pregnancy. Staying fit and well has many benefits for both you and baby - so keep up the awesome work mummy!
      Sophie, Tommy's Midwife

    • By Marie (not verified) on 30 Jan 2018 - 17:45

      Hi question I'm going to be a first-time mom and I want to know is it normal not to have any symptoms at all or have your LPM since November and if you have morning sickness one day and then the other day is gone is that normal or have you had a miscarriage but you do not bleed or anything just have morning sickness that one time and then it's gone but no symptoms at all the whole 2 months which Jan 27 made (2) months so I did blood work and test and it said that you're pregnant but don't feel any symptoms at all. Stomach felt tight and full one minute and feel normal the next had a few pelivc pain and light cramps nothing steady.. no period Since November 27th so is it normal to feel that way and not have any symptoms at all no nausea no vomiting just stomach and bathroom bowel movements? should I be worried about anything I'm praying all is fine and that no missed Carry or that the baby had stopped growing... Trying to stay calm and don't stress.. please help

    • By Midwife @Tommys on 31 Jan 2018 - 11:38

      Hi there Marie
      Many women experience no pregnancy symptoms at all. Whilst i can appreciate that this feels stressful, some would say that you are lucky as many pregnancy symptoms can make a woman feel quite unwell, especially in that first trimester. An absence of symptoms, does not make the pregnancy unhealthy or pose a risk to fetal development.
      If you wish to call and have a chat about this further, please feel free to call us on 0800 0147800
      All the best
      Sophie, Tommy's Midwife

    • By Princella (not verified) on 30 Jan 2018 - 09:14

      Ive had unprotected sex last two months(december) .My menses didnt show up this January and ive been excited that im already pregnant;only to wake up this morning to see my menses.When can i use a test stip ? Could it be that i wasn't pregnant ? Im confused. Please help

    • By Midwife @Tommys on 31 Jan 2018 - 11:19

      Hi Princella. I am sorry that you feel disappointed. It does not sound as if you are pregnant. If you do a pregnancy test whilst you are still menstruating, the result will only be negative - so please don't waste your money.
      You can look on our web page about pre-conception health- Please feel free to get in touch if you need any further advice.
      All the best
      Sophie, Tommy's Midwife

    • By Zanele (not verified) on 29 Jan 2018 - 18:30

      i had my last period on 20 jan, then have unprotected sex after 5 days my womb got cramps about 4 days now. pains in right abdomen now whole womb, no appetite

    • By Midwife @Tommys on 31 Jan 2018 - 09:54

      Hi Zanele
      Having had your last menstrual period on the 20th Jan 2018, the most pregnant you would be, is around 1 week. It is likely that if you took a test now, it may not show up yet. I would wait a week and then take a test. If the abdominal pains are very severe, and you are very concerned, then please go to your GP or local minors walk in center if out of hours.
      Please take good care of yourself
      Sophie, Tommy's Midwife

    • By LINDS (not verified) on 29 Jan 2018 - 10:52

      I am looking for a bit of advice. My last period was 25th Dec and haven't had one since. I took a test yesterday afternoon (clear blue) which confirmed I was pregnant and said 2-3 weeks. I took another test first thing this morning (first urine) and test confirmed preganancy however said 1-2 weeks. I am stressing as this doesn't seem normal. Can you please advise and offer some reassurance?

    • By Midwife @Tommys on 31 Jan 2018 - 09:48

      Hi Linds
      Using your last menstrual period date of 25/12/17 - the most pregnant you could possibly be is between 4-5 weeks. Pregnancy tests, no matter what brand, simply detect whether HCG (the pregnancy hormone) is present in the urine or not to give a positive or negative result. They cant really accurately date a pregnancy. For this to be 100% accurate, you will need to be scanned. So please do not worry about this.
      Please, if you have not already done so, make a GP appointment to inform them of your pregnancy so that your midwifery care can begin, and your first scan can be arranged. If you wish to talk anything through, feel free to call us on 0800 0147800
      Please take care of yourself.
      Sophie, Tommy's Midwife

    • By Thando (not verified) on 27 Jan 2018 - 18:31


      I have irregular periods, my last period was on the 19th Dec, I was expecting my period on the 14th Jan but nothing with my irregular periods I would have gone twice on my periods by now haven’t done a home pregnancy test I’m scared of getting my hopes high... I don’t have any symptoms but a pure white discharge.. please help.


    • By Midwife @Tommys on 29 Jan 2018 - 10:26

      Hi, The only way to confirm a pregnancy at an early stage is to do a pregnancy test. Don't be scared as a result either way will help you to understand what is happening. Best wishes

    • By fakazi (not verified) on 27 Jan 2018 - 18:18

      Hi my last period was on the 6 December, I'm 4rm the doctor he confirmed that I'm pregnant and he gave me pregamal n mapamol, can I also use pregnavit pills?

    • By Midwife @Tommys on 29 Jan 2018 - 11:12

      As far as I am aware, Pregamal is a brand name for a supplement which includes folic acid and iron. Pregnavit is also a brand name which includes both these ingredients. Therefore it is not necessary to take both. I am not familiar with mapamol but a similar name napamol is a brand name which includes paracetamol and is used for the management of pain and fever.

    • By Precious (not verified) on 25 Jan 2018 - 23:10

      I went to the doctor with random cramps took urine pregnancy test was negative but took a blood test was positive than a week later got a light period with period craps that started off as sporting and I was started o supliments I'm confused if I'm still pregnant or not

    • By Midwife @Tommys on 26 Jan 2018 - 10:22

      Hi Precious,
      I understand how confusing this must be for you and it is difficult to know for sure. The bleeding could be an implantation bleed which is very common in early pregnancy and presents as light spotting and can last for a few days. It is great that you are taking supplements and I would advise for you to continue to take these at the moment. As you had a blood test to confirm your pregnancy, it sounds like you need to be reviewed due to the bleeding, they may just repeat the pregnancy test or refer you to the local early pregnancy unit. I hope this helps, if we can support you further then please do be in touch.

    • By Kelly (not verified) on 25 Jan 2018 - 19:16

      Hi my last period was 7th DEC I had my implant taken out on the 1st but was bleeding a week before I had bar out the last date of period was 7th DEC how far would that make me I did a clear blue test it said 2-3

    • By Midwife @Tommys on 26 Jan 2018 - 10:44

      Hi Kelly,
      I understand that this is quite confusing and it is difficult to know exactly how many weeks pregnant you are. You state that your period started on the 7th of December, however this could be a withdrawal bleed due to having your implant removed. If this was a full period then you would be about 7+ weeks now according to that date. Your periods can change and be irregular when you stop contraception as the hormones are adjusting. It would be a good idea to see your GP and they can refer you for an early scan if the dates are uncertain. Also a reminder to be taking a folic acid supplement if you are not already. Take care x

    • By Anonymous (not verified) on 25 Jan 2018 - 06:51

      m I pregnant
      hi I had my last period on 5 December and m feeling week, no appetite nosea I feel as if something is on my throat. pliz help

    • By Midwife @Tommys on 25 Jan 2018 - 12:04

      Hi, Thank you for your comment.

      If you have missed your period since the last on in December and you have been having unprotected sex during this time, there is every chance that you may be pregnant. We would advise that you need to take a pregnancy test to see if you are indeed pregnant, if you are then the next step would be to go to the GP who can refer you to the midwife and your antenatal care can begin. Hope this helps, Take Care, Tommy's Midwives x

    • By nicola (not verified) on 23 Jan 2018 - 22:23

      hello my period ending on boxing day 2017 only last 4 days which makes my cyle 28 iv had sex mostly everyday without condoms and im one day late for my peirod my belly looks big and my boobs are always hard and i have now and then white discharge am i ready to take a test or wait for my period im really confused and dont know who to turn too many thanks

    • By Midwife @Tommys on 24 Jan 2018 - 14:48

      Hi Thank you for your comment.
      As you are a day late for your period and showing signs of pregnancy, then it is fine to take a pregnancy test. If you do it first thing in the morning, your first void of the day, then this will be the most concentrated to give you a result. If it is negative, leave it a few days, if your period still doesn't come then do another pregnancy test. Hope this helps, Take care, Tommy's Midwives x

    • By Lennaa2007 (not verified) on 24 Jan 2018 - 19:46

      Hi I need help my last period was 30th Dec I am due my cycle but I just no I'm pregnant this will be my 4 th pregnancy previously with my other 3 pregamcys I have had to have blood test done ... my first child I was nearly six months pregnant when I found out . Again this time round all test have came back negative, I have all the symptoms tired cramps really tender breasts food adhesions light handedness.... etc my question is I suffer with endometriosis I have 3 cysts present on my ovaries ... and I have been known to anaemia... how long should inwait to seek gp advice .

    • By Midwife @Tommys on 25 Jan 2018 - 10:41

      Hi, Thank you for your comment.

      If you feel that you are pregnant and you have on going gynaecological issues, then it would be advisable to be seen by the GP at the next available appointment that you can get. He will be able to do another blood test to confirm your pregnancy if a pregnancy test is coming up negative and then refer you on to the midwife to start your antenatal care if you are pregnant. Hope this helps, Take Care, Tommy's Midwives x

    • By By anonymous (not verified) on 23 Jan 2018 - 18:00

      Hi I my last period was 12/10 it was a week early I did 3 test and all said positive how long would I be please

    • By Midwife @Tommys on 24 Jan 2018 - 14:25

      HI, Thank you for your comment.

      If your last period was on the 10th December then you would be around 6 weeks pregnant.

      If your last period was on the 12th October then you would be around 14 weeks now.

      I am unsure if you mean October or December so I have given you both potential dates. If you are unsure of your dates then the GP can always refer you for an early dating scan do confirm how many weeks you are. Hope this helps. Take care, Tommy's Midwives x

    • By Racheal (not verified) on 23 Jan 2018 - 09:26

      Hello me and my partner had sex in Nov 22. Soon I got periods by Nov end. Again next periods was in Dec 22. Now its jan 23 and have still not got my periods ? Please confirm whether am pregnant as I get morning sickness. I have even vomited on Dec 22 for 3 days and then again on Jan 14. But I doubt this is due to food.

    • By Midwife @Tommys on 23 Jan 2018 - 13:27

      Dear Racheal,
      If you've been having unprotected sex there is a chance that you are pregnant. Buy a pregnancy test today and you will have an answer. Please get in touch again if you have any other questions.
      Good Luck!
      Anna-Tommy's Midwife

    • By Laura (not verified) on 20 Jan 2018 - 23:23

      Hi I'm roughly 8 weeks pregnant. Two weeks ago I started bleeding and passed a blood clot. I visited my doctor who did an ultrasound and physical examination and was told the baby is fine. However I've been spotting everyday and its getting darker in colour. I just need some advice on what to do. Thanks .

    • By Midwife @Tommys on 22 Jan 2018 - 11:55

      Hi, You could go back to your doctor to confirm the previous findings if you continue to bleed. A blood test may also confirm whether the pregnancy hormones are increasing. Many women have spotting in early pregnancy and go on to have a normal pregnancy. Best wishes

    • By shantel (not verified) on 20 Jan 2018 - 19:56

      My last period was December 22 . I was expected to have a period the week of January 15 I am now four days late. I took a pregnancy test but it came back negative.

    • By Midwife @Tommys on 22 Jan 2018 - 11:41

      It may be a bit soon to take the test. Try waiting a few days and then take another test if your period has not come.

    • By Natasha (not verified) on 20 Jan 2018 - 19:34

      Hi. I got off the pill in November and have been trying to conceive since then. I did my detox and started my folic acids. Ive been having sore breasts and itchy nipples in December and now I’m just very tired all the time and have severe back pains and usual nausea as well as frequent peeing.
      I use the Flo app to track my ovulation dates,but when I take an ovulation peeing test on the same day, it shows negative. I’ve also taken a pregnancy test and it was negative. I had a period that was shorter than my usual periods,is that spotting? Very unsure

    • By Midwife @Tommys on 22 Jan 2018 - 11:34

      No I think this is unlikely to be spotting as you would have a positive pregnancy test. Try not to worry yet. Although some women get pregnant as soon as they come off the pill, this is not true for everyone and it may take a few months until you conceive.

    • By Beauty zimik (not verified) on 20 Jan 2018 - 04:00

      I had unprotected sex on 14th and 15th of Dec, my period came on new year n ended on 5th of Jan, after my period ended we had unprotected sex for almost 7 days, my periods due date is on 1 of Feb, my concern is my stomach it feels tight, but I don't have any other symptoms of pregnancy , is it just bloating or should I run a test, is it too early?

    • By Midwife @Tommys on 22 Jan 2018 - 11:29

      There are some 'sensitive' tests that can confirm a pregnancy slightly before your period is due but mostly we recommend that you wait until your period is due and then do a test to confirm if you are pregnant.

    • By By Jay (not verified) on 18 Jan 2018 - 16:20

      Hello. I am 9 weeks pregnant I have been spotting since my 7th week of pregnancy and I am presently on bed rest. An ultrasound was taken and my baby is fine however I keep wondering why I am spotting. I also feel sick 24 /7 and very exhausted. Is this normal?

    • By Midwife @Tommys on 19 Jan 2018 - 12:41

      Hi, sorry to hear to are having a difficult and worrying start to your pregnancy. Some spotting in early pregnancy is common, and the cause of it is not always known. It is reassuring that you have had a scan however, and all you can do is look after yourself as best you can. IF the spotting increases or you have any pain then do go back to your GP or early pregnancy unit to be reviewed. Again feeling sick and exhausted is very common, it sounds like you are resting which is good, drinking enough water and eating little and often can help too. You should have your booking appointment with your midwife soon, at this they will take some bloods and part of the tests will be checking your iron levels, if this is low then this can make you feel even more tired and you may need to take some iron tablets. If you having on going concerns then do see your GP for a review and reassurance. Take care x

    • By Emily (not verified) on 17 Jan 2018 - 16:00

      Hi, me and my partner had intercourse in 4 jan he ejaculated completely inside of me also in 5 jan and 6 jan i took emergency pill on 7 jan on morning after 2 hours i found out im period. Did i still can get pregnant? On 15 jan i check on urine pregnancy test my result was negative.

    • By Midwife @Tommys on 19 Jan 2018 - 12:28

      Hi Emily,
      From what you have described, as long as you think it was a full and normal period that started on the 7th January then you would not be pregnant. Just to let you know that the morning after pill is most effective the sooner after intercourse it is taken. If you are having regular intercourse and want to avoid pregnancy then you can have a chat with the practice nurse at your GP or family planning clinic about contraception options. Take care x

    • By sam (not verified) on 16 Jan 2018 - 15:35

      hi, i am 5 weeks pregnant and before i was i had regular migraine attacks which I treated with effective medication prescribed by doctor. However my migraines have come back much stronger and frequently, I dont know what to do and how to treat it. I am worried! help!!

    • By Midwife @Tommys on 17 Jan 2018 - 13:30

      Hi Sam, i am sorry to hear about how you are suffering with migraines.
      It is really important that you tell the midwife about these at your booking appointment, but also please go to your GP asap to tell them that you are pregnant so that they can send a referral for you if they are concerned with your medical history in the past in relation to the pregnancy. They may also need to check that the medication you take for migraines is safe to take now that you are pregnant. Please take good care of yourself
      Tommy's Midwife

    • By Angela Cameron (not verified) on 14 Jan 2018 - 20:03

      I was pretty nauseous and randomly vomiting during my first trimester. I tried Reglan, vitamin B6 and Unisom but nothing helped alleviating my sickness. However, since I started drinking "No to Morning Sickness Tea" my symptoms vanished and I can eat and drink without getting nauseous or puking.

    • By Midwife @Tommys on 15 Jan 2018 - 14:32

      So pleased that you are no longer feeling nauseous. I just want to ensure though that you are aware to drink herbal teas in moderation. While there is little concrete evidence with which to advise, there are concerns that some herbal teas may be harmful if drinking in excess. And for those reading this reply, remember that for most women morning sickness will ease from around 12 weeks gestation. You may find this article useful

    • By Heather (not verified) on 9 Jan 2018 - 21:47

      I have been told all my life from about 16-17 on that I have PCOS and that I would most likely would have issues getting pregnant. I had some issues last year and an obgyn told me I most certainly would not get pregnant without help. Well, I haven't taken any fertility meds, my last period was around Thanksgiving and I was due again on Dec 26. No period....over 2 weeks later....5 positive pregnancy tests over 3 days. I'm so nervous that its not true but my breasts hurt, ive been queasy at times, SUPER tired all the time and Oh...moody and emotional times 10. I believe in God and miracle and that's what this baby would be. I guess we'll wait for confirmation at my 8 week appt scheduled in 2 weeks

    • By Midwife @Tommys on 10 Jan 2018 - 10:49

      Hi Heather.
      Congratulations on your pregnancy!
      Whilst Dr's are very knowledgeable - they are not 100% accurate all of the time. They look at risks and base their predictions on these. Having PCOS can make it hard for women to conceive - but not impossible. Your story is not an uncommon one.
      Good luck with everything! I really hope that you can enjoy your pregnancy! Sophie, Tommy's Midwife

    • By Alice (not verified) on 11 Jan 2018 - 00:07

      Hi! I can totally relate to this.
      I too was told I would never be able to conceive naturally without medical assistance /meds. My fiance and I continued to have unprotected sex for 5 years without getting pregnant until 7 weeks ago. I am now 7 weeks pregnant. It was a surprise but a welcoming one. We are ecstatic and looking forward to this journey. Never lose hope, our bodies are amazing and God is great. Good luck with your little miracle. Xo

    • By Midwife @Tommys on 11 Jan 2018 - 09:28

      Hi Alice, that is wonderful news - congratulations!

      Sophie, Tommy's Midwife

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