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 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.

    • By Holly (not verified) on 24 Aug 2017 - 17:38

      Hi I have a history of recurrent miscarriage all ending around 7 weeks. I also have had a uterine septum removal. I have been seen by Tommy's and have had reassurance scans which were all fine.

      I am 12+2 and had my find scan yesterday. Baby was fine and wriggling around. I had a bleed of bright red the day before the scan, this has now turned to spotting. Although the scan showed everything was fine I can't help but worry.

      I remember at my 6 week scan the sonographer said they could still see a small septum in my uterus. I know septums can cause first trimester miscarriages but wanted to know if they can effect the pregnancy after 12 weeks?



    • By Midwife @Tommys on 25 Aug 2017 - 16:49

      Hi Holly,
      It is totally understandable that you are still feeling anxious in this pregnancy. A uterine septum can still affect a pregnancy beyond 12 weeks as increases the chance of baby being in a breech position or you having a preterm birth however the smaller the septum the lower the risk therefore if you have had this corrected it sounds like the chance is low. If you are concerned then speak to your midwife or consultant for reassurance.

    • By Sid (not verified) on 24 Aug 2017 - 05:06

      I got my periods on 21 july till today i dont get my periods. I test at home, my result is positive . Im having cramps and little back pain. In other word im disliking everything except this great news. Is that normal? Plus can u calculate me weeks.

    • By Midwife @Tommys on 25 Aug 2017 - 16:44

      Hi , congratulations! But sorry to hear that you are experiencing some cramps and pains, this can be very normal in pregnancy, if these worsen or you have any bleeding then so see your GP or A+E if out of hours to be reviewed. If you are pregnant it is important to be taking folic acid and vitamin D if you are not already.
      To calculate your due date I will need to know the length of your cycle, you can use our calculator here:

    • By Anonymous (not verified) on 21 Aug 2017 - 11:44

      Hi I have spotting from 5 weeks till now 8 weeks and 3 days I had a scan at 7 week and 3 days saw a heartbeat. Is it normal to have spotting in pregnancy? What causes it? This is my 5th pregnancy I have not had a successful pregnancies so far.

    • By Midwife @Tommys on 24 Aug 2017 - 13:55

      Hi Thank you for your comment. It can be normal to have spotting during early pregnancy, this doesn't necessarily mean there is a problem. It could be from implantation or there maybe abrasions on the cervix that can bleed in pregnancy, or sometimes this cannot be explained and the bleeding settles down. It is very reassuring that your scan was positive and you could see a heartbeat but if you so start to have any bleeding or abdominal pain then please contact your local early pregnancy unit so that you can be seen and assessed. Take care, Tommy's Midwives x

    • By Anonymous (not verified) on 20 Aug 2017 - 12:43

      I saw my last period on date 3 of July.
      i tested on 12 of July it was negative.
      then i tested again 28 of July and i got it Positive. now I'm pregnant I'm feeling most of the feels i read here. so help me !
      how should i know my real time?
      thank you!

    • By Midwife @Tommys on 21 Aug 2017 - 16:56

      According to your last menstrual period date you would be 6 weeks and 6 days today. This gives a due date of 9/4/18. Try to arrange to see a health worker as soon as you can and you can arrange your maternity care. Best wishes

    • By anonymous (not verified) on 16 Aug 2017 - 19:21

      hi i last saw my period on 7th of july...
      last week i took home pregnancy test and it was +
      today im spotting
      is it normal?

    • By Midwife @Tommys on 17 Aug 2017 - 16:07

      Hi, some spotting in early pregnancy can be normal, this usually occurs about 4-6 weeks after your LMP and can last up to about 5 days and is an implantation bleed where the fertilised egg is embedding in the wall of the uterus. If the bleeding becomes heavier, you feel unwell or you have any pain then it is important to see your GP or contact your local EPU if you can self refer to be reviewed. It is also important that you are taking folic acid supplement, if you have not been taking it this far, do no worry but try to get some as soon as possible and be taking it until at least the end of the first trimester.

    • By Anonymous (not verified) on 2 Aug 2017 - 18:55

      Good day pls im around 7 weeks pregnancy. i just want a prescription of the drugs that will be good me and my baby. Thanks.

    • By Midwife @Tommys on 3 Aug 2017 - 11:55

      Hi, Thank you for your comment.

      It all depends on what medication you need and if it is safe to take in pregnancy. It would be advisable that you see your GP or midwife who can discuss this with you further and if you need any medication changing for pregnancy. Take Care, Tommy's Midwives x

    • By Anonymous (not verified) on 2 Aug 2017 - 18:35

      My last period started on the 12th June. I've taken 4 tests and they're all +ve. However, I'm really having trouble accepting its true. Can you get false positives? I've read you can and I'm really worried that if I had a kidney infection (I recently went away camping and didn't feel well plus a dull ache in the kidney area) it could be causing a false positive. The DRs don't really want to know and have just booked me a midwife appointment in 3 weeks time. Am I actually pregnant do you think?

    • By Midwife @Tommys on 3 Aug 2017 - 11:48

      Hi, Thank you for your comment.

      It can be a very strange time when you find out that you are pregnant and like you say it almost doesn't seem real. This can be normal in the early stages, especially if you are feeling well and not experiencing any sickness. If you have missed your period and then taken 4 pregnancy tests which have all come back positive, then it is highly likely that you are pregnant. Make sure that you are taking pregnancy vitamins, eat well and drink plenty of fluids. If you have any further questions then you can always email the Tommy's midwives on [email protected] or call us on 0800 0147 800 Monday to Friday 9am-5pm. Take care Tommy's Midwives x

    • By annon (not verified) on 27 Jul 2017 - 16:38

      Am 12weeks pregnant but my Gp gave me folic acid at 10week is this not going to cause anything on my beautiful soul inside me...but been taking oranges alot since 2weeks because of some cravings ofcoz. ..

    • By Midwife @Tommys on 28 Jul 2017 - 11:05

      Hi, many congratulations on your pregnancy. Folic acid is recommended to take in pregnancy for at least the first 12 weeks and it is in many of the pregnancy multivitamins too. It is recommended to help with your baby's development and prevent certain conditions so we would recommend for you to have been taking it.

    • By Anonymous (not verified) on 11 Jul 2017 - 20:52

      I just got to know that I have uti and along with that recently I got to know that I am expecting so I want to know if I will take medicine for uti will it create a problem for me please suggest me m worried about it because I can't stop the medicine for uti because it's very painful nd gives me uneasiness and discomfort,thanks

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

      Hi Thank you for your comment.

      You should go back to the doctor who prescribed you the antibiotics to see if they are safe to take in pregnancy. A few antibiotics are safe to take so if the doctor needs to change them then he will.

      It is important to treat any infection in pregnancy so you should be on antibiotics until the urine infection has gone. Try to drink plenty of fluids to help pass the infection. Please contact the GP as soon as you can. Best wishes Tommy's Midwives x

    • By Sara (not verified) on 5 Jul 2017 - 06:58

      My last period date is 16 May...this month I miss my periods...after checking that result is which month it consider n with whom I concern about it. I mean till now don't concerned with doctor. N I feel very lazy ever time n nothing want to eat ..every time feel vomiting kind...mostly face gas problem

    • By Midwife @Tommys on 5 Jul 2017 - 14:48

      Thank you for your comment
      At the moment you are approximately 7 weeks pregnant. We advise that you contact your GP or maternity unit as soon as possible so that you can be referred for antenatal care which can start from 8-12 weeks with your Midwife booking appointment and then dating scan from 10-12 weeks.

      Feeling sick and tiredness are common early pregnancy symptoms-its important to look after yourself, by having a healthy diet for example. if you are finding it difficult to eat much, then small frequents meals, avoiding foods that are too fatty or strong tasting may help. If you are vomiting and cannot keep water down, then you would need to seek urgent advice from A&E or your GP.
      I have attached 2 links that you may find helpful

      Please do not hesitate to contact us again or call our PregnancyLIne
      0800 0147 800
      Hope this helps
      Tommy's Midwife

    • By salomi (not verified) on 4 Jul 2017 - 17:37

      Hii my last period is 11th may. We had unprotected sex but I m very sure that it is not fertile period. I hav tested on 25th June. But the result is negative. Is there any possibility for me to be pregnant? Can u explain y?

    • By Midwife @Tommys on 5 Jul 2017 - 12:02

      Thank you for your comment
      If the pregnancy test was negative it is still possible that you are pregnant
      The following information is from our website and I have attached a link with more advice for you
      ' How accurate is the pregnancy test?
      It is important to know that whilst a positive result is likely to be accurate, a negative result may be misleading. Some women have a negative result and test again a week later to find that it is positive.
      This is due to the levels of pregnancy hormone gradually building up to a level at which they can be detected. If you test yourself very early on and you have a negative result, you should carry out another test in 2-3 days’ time if you have still not had a period.
      If you continue to get negative results and still no period, you should consult your doctor'

      Hope this helps
      Tommy's Midife

    • By Anonymous (not verified) on 28 Jun 2017 - 16:23

      my last periods were on 9th of May 2017 and am having chest pains and always feeling tired...isn't too early for all this

    • By Midwife @Tommys on 29 Jun 2017 - 14:45

      Hi, Thank you for your comment. Feeling tired in the beginning stages of pregnancy is very common and it is important to listen to your body and rest or sleep when you can. With regards to the chest pains, we wouldn't expect you to have chest pains in pregnancy unless it could be heartburn and indigestion. It may be that this chest pain is not related to pregnancy so if you are having chest pain then it is advisable to seek medical advice either from the GP or if you think these pains need looking at sooner then we would advice you to go to A and E. Hope this helps and you start to feel better soon. Tommy's Midwives x

    • By Anonymous (not verified) on 27 Jun 2017 - 12:22

      Hi, I recently did a home pregnancy test 3 times and they all came back that i was pregnant. Last day of period was 17th May so I am thinking I am 6 weeks, is that right?
      I am going back to Australia in August but I am desperately trying to get an appointment with a GP but because I don't have proof of address no one is seeing me, the hospitals have told me I need a referral from GP before I go see them and i spoke to a midwife this morning who told me that they cant do anything with early pregnancy that I have to wait a few weeks. I am really stressing out that no one can help me. My boyfriend and I are living at an address but are not meant to be at that address and unable to register at local GP. Could you please give me some advice, I need to see someone asap!!!

    • By Midwife @Tommys on 27 Jun 2017 - 12:33

      Hi there,
      It is difficult to register at a GP if you are not living in the property for the foreseeable future. You do not need to access midwifery care until you are 8 weeks pregnant or more though as they will be no additional care up until this point anyway for any woman.
      The easiest way to make contact with a midwife- bypassing the GP, is to google the hospital that you would like to start your maternity care with and look for a direct number/email for them. It is likely to be called "direct access to a midwife" or contact a midwife etc. Most U.K hospitals have a telephone number or email address for you to make contact with a midwife. The first booking in appointment with a midwife needs to take place between 8-12 weeks gestation- you will be scanned after this appointment between 11-13 weeks.
      If you need more information on this, please feel free to call us for more advice on 0800 0147800

    • By Anonymous (not verified) on 24 Jun 2017 - 18:26

      Hi my last period was 29 April , but no period since ( regular 28 days ) on the 3rd June I had some spotting , I'm not on any form of contraception , I feel out of sorts with myself , today iv been feeling nauseous but not being sick ( but I was never sick with my other children) , iv had constipation , my partner says iv been having mood swings , iv been emotional ( crying ) , I'm unsure weather it's pregnancy or menopause , my mums past away so iv no one to ask , please help .

    • By Midwife @Tommys on 26 Jun 2017 - 11:38

      It is not possible to confirm a pregnancy at this stage without a pregnancy test but you could be as much as 8 weeks pregnant. The most likely age to reach the menopause is 45-55 but it is certainly not impossible for it to be earlier. If you are not able to do a home pregnancy test are you able to see a doctor for confirmation?

    • By zuri (not verified) on 14 Jun 2017 - 01:55

      My last Period was 29 March. I took a pregnancy test it was positive and showed 3+ weeks in April. Now am feeling my Tammy is very sore sleeping is a problem, am even having difficult wearing any thing with elastic, and my Tommy is showing already I thought the bamp will show after 12weeks is this normal. I haven't gone to the doctor yet coz I still have some issues to sort out with my medical insurance. Is what am feeling normal and why do I have to go to the lu many times

    • By Midwife @Tommys on 14 Jun 2017 - 11:42

      Hi Zuri,
      Please get seen by your doctor or midwife today as you are already coming to the end of your first trimester and need to start antenatal care as soon as possible. you need to know what your options are in regards to scans and blood tests. Going to the loo so many times may just be due to early pregnancy but I would want to check that you haven't got a urinary tract infection as well. You can also call us here at Tommy's and talk to a midwife on 0800 0147 800 or email us on [email protected]
      Hope to hear from you soon
      Anna-Tommy's Midwife

    • By Rosy (not verified) on 13 Jun 2017 - 19:06

      My last period was on 27th April, on 25th may I saw period for a day and half and I had unprotected sex this two months. Please am I pregnant. Am afraid to do pregnancy test.

    • By Midwife @Tommys on 14 Jun 2017 - 10:36

      Hi Rosy,
      If you have been having unprotected sex over the last two months it is possible that you are pregnant. You mention a period but this seems very short lasting.
      I appreciate that you are feeling frightened but if you don't do a pregnancy test you won't know whether or not you are pregnant and if you are you can get support and find out what options are available to you. Please buy a test today and call us if we can be of any support to you on 0800 0147 800.
      Anna - Tommy's Midwife

    • By Rosy (not verified) on 13 Jun 2017 - 18:12

      My last period was on 27th April, on 25th may I saw period for a day and half and I had unprotected sex this two months. Please am I pregnant. Am afraid to do pregnancy test.

    • By Anonymous (not verified) on 8 Jun 2017 - 11:51

      I saw my last period on d 3rd of May 2017,always 28days.And in June 5th i saw it again is it possible to be pregnant?pls help me easy my worries.

    • By Midwife @Tommys on 8 Jun 2017 - 12:03

      Hi, if you have not missed a period then you shouldn't be pregnant. If the period that you have had in June was a normal period for you, then again you may not be pregnant. If you have been having unprotected sex then there is a chance of a pregnancy but you have not missed a period so the likelihood of you being pregnant is relatively low. That's not to say that in some cases women don't miss a period or have some bleeding and they are pregnant. If you think that you may be pregnant then you can always take a pregnancy test, but again you haven't missed a period, so being pregnant is highly unlikely. Hope this has reassured you a little. Take Care, Tommy's Midwives x

    • By Anonymous (not verified) on 5 Jun 2017 - 05:33

      Hi I am trying to get pregnant for the longest while I did an ultrasound and it shows all my organs are good in shape and size what is going wrong I had sexual I intercouse to with my husband the day after my last cycle finish can I get pregnant that way or will I become pregnant

    • By Midwife @Tommys on 5 Jun 2017 - 11:53

      Hi. How long have you been trying to get pregnant? In the UK we recommend that couples try for a year before we suggest that they see a doctor for advice. Have you seen our page on 'getting pregnant' ? It may help.

    • By Nkiruka Chiemezie (not verified) on 30 May 2017 - 12:57

      If my last period was on the 18th of april,how many weeks pregnant am i?

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