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.


Follow Tommy's PregnancyHub on Instagram

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 Midwife @Tommys on 13 Feb 2018 - 15:20

      Dear Grace
      Thank you for your message.
      Some abdominal pain and mild cramps are common in early pregnancy, however they should all be checked by a midwife or doctor - please contact your midwife/doctor to arrange an appointment to be checked.

    • By Kaija (not verified) on 9 Feb 2018 - 08:25

      I just found out I'm pregnant I had my last cycle at the end of December 30 begin Jan I just found out I'm pregnant three days ago how far along am I and I'm wounder around what date I got pregnant can someone help me

    • By Midwife @Tommys on 9 Feb 2018 - 15:54

      Hi Kaija,
      According to the dates that you have provided, based on you having a regular 28 day cycle, if the first day of your last period was 30 December then it would make you about 5 weeks and 6 days pregnant. It would be likely that conception occurred the days around the 14th of January. I hope that makes sense, if you would like to talk further then please do email us [email protected] Best wishes, Tommy's midwives.

    • By Gemma (not verified) on 7 Feb 2018 - 22:01

      Hi I’ve just found out I’m pregnant I haven’t had a period since the 5th Dec... I had a blood test and my hcg levels are 72’000 I’ve also had a scan which shows it’s twins and heartbeats were detected but my gynaecologist says I’m only 4-5 weeks pregnant is this possible?

    • By Nani (not verified) on 7 Feb 2018 - 04:27

      Hello I had my last period on around December 21st and took 4 home pregnancy test the 1st 3 i took on January 25th and were positive but not that clean. The last one was on February 1st and was more clear but the week after my missed period i felt like this fullness as if I were about to have a heavy period but nothing along with cramping and after intercourse i start brown spotting throughout the day and still have some cramping throughout the day is this normal?

    • By Midwife @Tommys on 7 Feb 2018 - 11:25

      Hi Nani
      It sounds like you may be best to go to your GP to have one more pregnancy test done there to be 100% sure.
      If you have cramping and spotting and are pregnant, then the GP should refer you to your local early pregnancy assessment unit for review there. If you are not pregnant, then you may be considered to be sent for Gyane testing if the GP is concerned by your symptoms and medical history. Please take care of yourself
      Sophie,Tommy's Midwife

    • By Hat (not verified) on 5 Feb 2018 - 16:35

      So I’ve been having unprotected sex with my partner for 3 months now my last period was the 8th jan I was supposed to be due on today which is the 5th Feb and this morning as I wiped it was pink blood then nothing else I’ve been feeling a little dizzy an sick lately on an evening does this sound like I’m pregnant ?

    • By Midwife @Tommys on 7 Feb 2018 - 11:22

      Hi Hat
      It would be sensible for you to do a pregnancy test to be sure. It sounds as if you and your partner are trying to conceive, so this does sound possible.
      The pink loss could also simply be the start of your period. So both options are possible.
      Feel free to get back in touch if you need more support or advice.
      Sophie,Tommy's Midwife

    • By Sheila Davis (not verified) on 5 Feb 2018 - 12:22

      Please help the start of my last monthly was November 16, 2017. I should have started my next monthly on December 26, 2017. That day all I did was streak. In January my monthly still hasn't showed up. I have taken to home pregnancy test both came back negative. I also have had a blood test done also negative. I have all of the signs of being pregnant. Could I be pregnant and it not show up on either test.

    • By Midwife @Tommys on 7 Feb 2018 - 11:19

      Hi Sheila
      It would be best to go to your GP to discuss this further. If you are 100% not pregnant, then the GP needs to refer you on for a Gynaecology review at your local hospital as you could have some type of hormonal imbalance that needs addressing. Please do not worry about this at this stage, changes can occur in menstruation patterns, but these are always worth getting check out to put your mind at ease! Please feel free to call us if you need to talk things through
      Sophie,Tommy's Midwife

    • By bebe (not verified) on 31 Jan 2018 - 10:12

      i last had sex on 6 January this year. and my last period was somewhere on the 16/17th DEC but haven't had any since ,got tested twice it came back negative but been having cramps and back aches,feel bit dizzy at i exaggerating?

    • By Midwife @Tommys on 31 Jan 2018 - 11:50

      Hi Bebe. The most pregnant you could be is only 3- 4 weeks maximum.
      It might be best to go to your GP to get another test to be 100% sure. And also if you are not pregnant, you may need a referral to a gynecology specialist if these episodes are happening due to your menstrual cycle/changing hormones.
      Take good care of yourself
      Sophie, Tommy's Midwife

    • By Leann (not verified) on 31 Jan 2018 - 02:40

      Hi, I just found out 3 days ago I’m pregnant and I have type 2 diabetes my sugars are usually 250/300 I eat well and exercise but I can’t keep them down. I was told I’m high risk due to being diabetic, I’m going to see a specialist but I’m very concerned about my baby what could happen to the baby??

    • By Midwife @Tommys on 31 Jan 2018 - 11:46

      Hi Leann. Congratulations on your pregnancy. Please don't panic about your diabetes - pregnancy is a time of change that does need to be managed, but many pregnant women with diabetes have a happy and healthy 9 months.
      Please go to your GP asap since you know that you are pregnant to discuss referral to a specialist team in pregnancy (due to your diabetes) and to be booked in for your first scan.
      Please feel free to call us if you wish to discuss anything further
      Sophie, Tommy's Midwife

    • By LeAnn (not verified) on 1 Feb 2018 - 21:58

      I have an appointment on Monday to see the specialist. I pray all goes well! Thank you for your help!

    • 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

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