First trimester: weeks 1 to 12

You're pregnant: congratulations! The first weeks of your pregnancy are a vital time as your pregnancy gets established. While you get used to being pregnant, your body is 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!

Lifestyle changes in the first trimester of pregnancy

You may need to make some lifestyle changes now that you are pregnant. Find out which foods and medicines you should avoid to keep your baby safe and healthy. You’ll also need to cut out alcohol and smoking, and reduce your caffeine intake.

You might be surprised to learn that caffeine is not just found in coffee, but also in tea, chocolate and energy drinks! Find out how much caffeine is in your daily diet.

Get your free guide to healthy eating straight to your inbox.

Try not to worry if you smoked or drank alcohol before you found out you were pregnant. Now that you know, you can take steps to looking after yourself and your baby.

Get help to stop smoking.

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. But try not to worry, these symptoms mean that your baby is growing strong and healthy!

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. 

Read more about mental wellbeing in pregnancy.

Find out more about the first trimester


1. NHS Choices (2012). “Your pregnancy week by week”. National Health Services: Choices. Accessed online on 02.02.2015: Page last reviewed: 22/07/2014. Next review due: 22/07/2016

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

3. NICE (2008). “Antenatal care: NICE clinical guideline 62”. National Institue for health and care excellence 2008; accessed online on 15.01.2015: (last review August 2014). 

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Last reviewed on April 1st, 2015. Next review date April 1st, 2018.

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  • 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 Anonymous (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 Anonymous (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 Anonymous (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 Anonymous (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 Anonymous (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 Anonymous (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 Anonymous (not verified) on 30 May 2017 - 12:57

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

  • By Midwife @Tommys on 31 May 2017 - 11:21

    Hi Nikiruka
    Congratulations of your pregnancy. Using the link below, you can enter the 18th april as your last menstrual period date, as well as the average length of your cycle to work out roughly how many weeks pregnant you are and to get your estimated due date. Please take good care of yourself!

  • By Anonymous (not verified) on 29 May 2017 - 19:10

    hi i saw my last period on 28 april when i went for a test on 27 may i was pos so how many weeks is my pregnant thenks

  • By Anonymous (not verified) on 25 May 2017 - 14:34

    I want to know how many weeks pregnant I am.I saw my period last on April 8.

  • By Midwife @Tommys on 25 May 2017 - 16:37

    Hello! If the first day of your last period was on the 8th April, then you are nearly 7 weeks pregnant. If you have had a positive pregnancy test then you need to see the GP, who can refer you to the midwife. Take care Tommy's Midwives x

  • By Midwife @Tommys on 31 May 2017 - 11:12

    Hi, using the link below, you can work out your estimated due date and roughly how many weeks pregnant you are by using your last menstrual period date of the 8th april, and putting in your average menstrual length cycle. Congratulations!

  • By Midwife @Tommys on 31 May 2017 - 11:12

    Hi, using the link below, you can work out your estimated due date and roughly how many weeks pregnant you are by using your last menstrual period date of the 8th april, and putting in your average menstrual length cycle. Congratulations!

  • By Anonymous (not verified) on 15 May 2017 - 21:51

    I've just found out I'm pregnant but unsure of how far gone I am. I had a 4 day mens cycle (which is normal) march 2017 and a day and 1/2 mens cycle at the beginning of April. Gp doesn't know how many weeks I could be , midwives haven't been in contact. Any ideas?

  • By Midwife @Tommys on 17 May 2017 - 09:27

    Hi there.
    It might be necessary to date your pregnancy via Ultrasound scan if your dates are uncertain.
    You can try our pregnancy calculator - see link below- using your last menstrual period date as your april period, and give your average length of menstrual cycle. That will give an estimation of how many weeks pregnant you might be. But an ultrasound scan will be more accurate.
    You can contact your local midwifery service via your local hospitals website if you have still not got a midwife booking appointment and you are concerned.
    Please take good care of yourself

  • By Anonymous (not verified) on 12 Jun 2017 - 14:12

    I had my period on 28 April bt May I did nt got intil me my period nvr come why everybody reply I need to knw

  • By Midwife @Tommys on 12 Jun 2017 - 14:32

    Have you done a pregnancy test? If your periods are regular and you have had unprotected sex there is a chance that you could be 6 weeks pregnant. An ultrasound scan would confirm your dates. Glad that you have found our site. Please look after yourself and follow the health advice that we provide. Best wishes

  • By Anonymous (not verified) on 14 May 2017 - 15:22

    um pregnant n I want to know he far I am .I had my last period on the1st of April so how far can I be

  • By Midwife @Tommys on 15 May 2017 - 11:01

    We use the last menstrual period to calculate your due date. If this was April 1st your due date will be 7th January 2018 making you 6 weeks plus 2 days today. Your first scan appointment will confirm the date for you.

  • By Anonymous (not verified) on 13 May 2017 - 18:33

    Hello I'm 37 and have PCOS. It took 3 years and IVF to conceive my 19 month old daughter, who I still breastfeed twice a day. I developed post natal hypothyroidism. I recently started metformin to TTC. Today by some miracle I got a positive home pregnancy test-I am 4w4d. This week I also got a call from the doctors telling me to reduce my thyroxine as I've gone hyperthyroid now. TSH 0.07, T4 19.2 and T3 4.4. It'll take 4 weeks for my reduced size to take effect. My sister has had two miscarriages (you have helped her, thank you) and has just been found to be hyperthyroid. Whilst I am over the moon and staggered that I have conceived naturally, I am so anxious about miscarriage. I've had very light brown (barely a tint) discharge since 10dpo and I had one red spot at 10dpo. All pregnancies are precious and this one is a miracle to me - I need to know what I can do to ensure my thyroid levels don't risk my pregnancy. I've some progesterone left over from IVF so I'm going to use them up for the next week. Also, should I stop breastfeeding my daughter? Thank you so much-it's Saturday so my doctors are shut (and are not great with endocrinology or fertility issues)

  • By Midwife @Tommys on 15 May 2017 - 13:12

    Hello and congratulations on your pregnancy. I would suggest that you make an appointment to see your GP as soon as possible and discuss the thyroid levels in the context of the pregnancy.
    In the mean time I cannot advise that you take the progesterone tablets that you have left over. Although the BNF states that these tablets are not known to be harmful, studies have shown that progesterone tablets do not really prevent miscarriage. In addition the medication may require storage in a fridge or cool area to maintain it's potency. In a spontaneous pregnancy it is thought that the ovaries will produce enough progesterone to maintain the pregnancy naturally.
    How lovely that you are still feeding your daughter. You can continue with this for as long as you and she wants to. You may find of course that she instinctively stops on her own. Some people believe that the taste changes in a pregnancy and the toddler no longer wants to feed. All the best Tommy's midwives x

  • By Anonymous (not verified) on 12 May 2017 - 14:43

    Hi,my last period was on 12th April and lasted for 3days which is not suppose to be so,my period normally last for 5days,untill now i hve not seen my period till now which suppose to come on the 11 (bin yesterday),i don't know if am pregnant cos feeling fuller nd bloat....though,i've not done d pregnancy test....
    But,could it be am pregnant?

  • By Midwife @Tommys on 15 May 2017 - 12:38

    Sometimes periods can be irregular and this is not something to worry about but if you think you could be pregnant I would suggest that you do a pregnancy test to confirm either way. x

  • By Anonymous (not verified) on 10 May 2017 - 07:42

    I had my last menses around 4th April 2017 and ended on the 10th of April... I have not seen my menses this month and today is 10th May will it be a pregnancy because I tasted positive when I did a
    home test old is the pregnancy now

  • By Midwife @Tommys on 10 May 2017 - 09:21

    Hi Nancy,
    Using our pregnancy calculator below, you can find out roughly how many weeks you are by putting in the date of the first day of your last menstrual period, as well as your average length of menstrual cycle- this will calculate a rough due date and how many weeks pregnant you are currently.
    Congratulations! Please do take care of yourself!

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