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

Hide details

Waterbabies logo

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

Was this information useful?

Yes No


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 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

  • By Anonymous (not verified) on 11 Jan 2018 - 04:03

    Congratulations!!! I'm a very similar situation but my doctor told me with the right nutrition regiment and diligence I could do it on my own. I am a week behind you! Good luck and yes it's true lol I'm in the same boat ... the 8 wk appointment will make it sink in.

  • By Midwife @Tommys on 11 Jan 2018 - 10:12

    That's great news! Congrats! Sophie, Tommy's Midwife

  • By Ms. Blackseed (not verified) on 17 Jan 2018 - 12:47

    Hi Heather
    I was told the same thing from my dr. I thought I will never get to experience becoming a mother. I just find out Dec 31 so it was great news bring in 2018 I'm so happy I really can't believe it and I feel this baby is a blessing to me

  • By Midwife @Tommys on 17 Jan 2018 - 14:52

    Hi Ms. Blackseed
    That's great news! What a great start to the year!

    Sophie, Tommy's Midwife

  • By Tina s (not verified) on 8 Jan 2018 - 16:39

    Hi,I had sex with my partner and the condom broke and he ejaculated completely inside of me.I took emergency pregnancy pills that day,then I took a blood test 10 days after and it was negative.and my period came back on time but it was a little lighter than usual.I took a home pregnancy test 6 weeks after and a blood test 11 weeks after.I’ve had 3 periods since on time but they were all a little lighter than how they used to be.they last about 5 days(and i do pass clots).is it possible I might be pregnant?

  • By Midwife @Tommys on 10 Jan 2018 - 10:45

    Hi Tina
    If you took the morning after pill, have done numerous negative pregnancy tests and blood tests and have had x3 normal (yet light) periods - then i think it is very safe to say that you are not pregnant!
    Please stop worrying.
    Sophie, Tommy's Midwife

  • By NITA (not verified) on 7 Jan 2018 - 21:50

    I was supposed to start my last period Dec.28-Jan.5... though it didn't come. Since the last week of Dec my breast has become extremely tinder an swollen... but I didn't think anything of it because I have an irregular cycle. So my husband on Jan.5 took me to get two home pregnancy test which came back positive. I haven't yet went to see my doctor yet to confirm with a blood test. Though I've been having cramps and sharp pains in my abdominal area, I also run out of breathe more now but I do have bronchitis. Should I be worried ? What should I do next?

  • By Midwife @Tommys on 8 Jan 2018 - 16:12

    It is quite common to feel period like abdominal cramps in early pregnancy and for many women this resolves after a few days. If it doesn't resolve or increases in strength, try to see your GP. If you are unwell with bronchitis I would also suggest you see your GP. Hope you feel better soon.

  • By Anita (not verified) on 6 Jan 2018 - 17:24

    Hi. Am 6weeks pregnant,,,I am vominting too much. Surprisingly my weight has dropped by worry is, what about my babies development?. Can I start taking iron supplements early?

  • By Midwife @Tommys on 8 Jan 2018 - 16:04

    Hi, If you are vomiting all the time and not able to keep even fluids down, I suggest you see your GP. Sometimes we have to admit women with hyperemesis to hospital if they become dehydrated. Try not to worry about the baby as he/she will not really be affected by the condition.

  • By Blessing (not verified) on 5 Jan 2018 - 12:25

    Hello, I work in a financial institution and usually get to the office as early as 7:00am, I am 11 weeks pregnant, my belly is still not out and I find it difficult waking up early. What can I do to help myself.

  • By Midwife @Tommys on 8 Jan 2018 - 15:49

    There are many of us who would sympathise but we don't have an excuse!
    Getting up early when it's cold and dark is hard enough, but women in early pregnancy feel especially tired and need more sleep. I would suggest getting to bed early and making sure that you eat good nutritious food. Avoid caffeine as although this can temporarily wake you up, in the long term it can make you more tired. Try to get some fresh air if you can and lastly don't be too hard on yourself. This extreme tiredness often resolves by 14 weeks. Best wishes

  • By Sarah (not verified) on 3 Jan 2018 - 23:56

    My last mestruation was 16th November, I have done a blood test and it’s positive, from your calculations how many weeks am I ?

  • By Midwife @Tommys on 4 Jan 2018 - 16:12

    Hi Sarah, Thank you for your comment.
    Congratulations on your pregnancy. If the first day of your last period was on the 16th November then you should be around 7 weeks pregnant. If you are unsure of your dates then you can always see your GP who can refer you for a dating scan. Hope this helps. Take Care, Tommy's Midwives x

  • By Sarah (not verified) on 7 Jan 2018 - 21:10

    7 weeks 3 days

  • By Terea (not verified) on 3 Jan 2018 - 14:14

    Hi back in Aug I had a misscarriage and had a D&C . My last full period ended on Nov 10th. I was supposed to have my next period on Dec 1st. I only spotted really light on dec 3rd and then nothing else. I started getting really sick on Dec 26 with all day nausea. And went to my local er on the 30th cause it hadn’t gone away. They said I’m pregnant. I’m pretty scared

  • By Midwife @Tommys on 4 Jan 2018 - 16:06

    Hi Terea, Thank you for your comment.

    We are so sorry to hear about your miscarriage in August. It is understandable that you are feeling scared in this pregnancy. Please be reassured that having 1 miscarriage doesn't put you at an increased risk of having another miscarriage this time. It sounds like you have pregnancy sickness so try and drink plenty of fluids and eat little and often. If you are still worried then you may want to visit your GP who can refer you for an early reassurance scan. Try and take each day at a time, it isn't easy when you are pregnant again after a miscarriage and your midwife will understand your anxieties. Be open and tell your midwife or GP if you feel like things are becoming overwhelming as they will be able to offer you additional support. You can always call the Tommy's Midwives on 0800 0147 800 Monday to Friday 9am-5pm or email on [email protected] Take Care, Tommy's Midwives x

  • By Tyty (not verified) on 1 Jan 2018 - 02:05

    My last.period was 18th of Nov 2017 and my circle is normally btw 28/38 i have done 2 test in the last few days but comes out negative my appetite has changed feeling in the morning and sometimes during the day could it be what am thinking.

  • By Midwife @Tommys on 2 Jan 2018 - 09:13

    Hi, thanks for your post. Your cycle has obviously changed but if you have had two consecutive negative pregnancy tests in the last two days it is unlikely that you are pregnant. What else is going on for you? Sometimes stress will affect your menstrual cycle. I am not sure whether you are planning to become pregnant or not wanting to get pregnant at present?
    The advice is obviously different depending on this.
    If you need to talk please call us on 0800 0147 800
    Thank you
    Anna-Tommy's Midwife

  • By Tina (not verified) on 30 Dec 2017 - 14:20

    I will be 8 weeks tomorrow and while I have been having mild morning sickness since the end of week 5 it has subsided since yesterday. I have also been rather emotional since yesterday. Should I be worried that I haven't been feeling morning sickness in about 24 hours ?

  • By Midwife @Tommys on 3 Jan 2018 - 09:09

    Hi Tina
    No, this is completely normal and nothing to be concerned about. Pregnancy symptoms can come and go and this is not uncommon at all. Feeling emotional also goes hand in hand with pregnancy as your hormones will fluctuate a great deal. You sound like a textbook pregnant woman. Congratulations! Sophie, Tommy's Midwife

  • Pages

Add new comment