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!

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.

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. 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. 

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.

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

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

Sources

1. NHS Choices (2012). “Your pregnancy week by week”. National Health Services: Choices. Accessed online on 02.02.2015: http://www.nhs.uk/conditions/pregnancy-and-baby/pages/pregnancy-week-by-week.aspx#close 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: http://www.nice.org.uk/guidance/cg62/resources/guidance-antenatal-care-pdf (last review August 2014). 

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

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Comments

  • By Julie (not verified) on 17 May 2018 - 12:40

    I had a normal period 11/02/18 My next period I had a strange period 08/03/18 I had one day of brown blood and the next day red blood but not alot followed by 2 more days of brown blood. I didn't have a period at all 02/04/18 I found out I was pregnant on the 5th of April clear blue pregnancy test said 2-3 and I tested again on the 9th it said 3+. I m now 10 weeks 3 days pregnant 17/05/18 I have my dating scan on 23/05/18. I don't know if these dates are right.

  • By Midwife @Tommys on 17 May 2018 - 14:50

    Hi Julie, Thank you for your comment.

    If you take the first day of your last period as the 08/03/18 then these dates sounds about right and puts you just over 10 weeks today. When you go for your dating scan they will be able to give you a more accurate date as it is easier to date a pregnancy within the first 12 weeks. Hope that this reassures you and if you have any further concerns then please email us on [email protected] Take Care, Tommy's Midwives x

  • By Sd2896 (not verified) on 14 May 2018 - 05:41

    Hi there
    Lmp was 8th of april 18
    Currently measuring 5 weeks and 1 day
    As today was my first time at my GP, and had a blood test, returning tomorrow to my GP to do more testing for glucose fasting was just wondering how long i have to fast for?
    Bit blury brain as i was trying to take in all the information i was given haha.

    And also will my GP reffer me to a midwife or do myself and partner choose for ourselfs?

    Thank you x

  • By Midwife @Tommys on 14 May 2018 - 12:04

    Hi, Congratulations on your pregnancy. Just give your surgery a ring to ask about the blood test. It depends what test they are doing as to how long you should fast for. Most fasting blood glucose tests require you to fast for 8-10 hours.
    You are able to choose your own care provider. The GP should be able to discuss this with you and will then send a referral. Alternatively you can self refer to a hospital of your choice.

  • By Patricia Ojonoma (not verified) on 12 May 2018 - 14:03

    My LMP was 23/3/2018. How many weeks am I and when will be my EDD? I also noticed a coloured discharge (blood like) yesterday hope all is well with my baby. At what month should I start Antenatal?

  • By Midwife @Tommys on 14 May 2018 - 11:34

    Hi Patricia, You would be 7+ weeks now and your due date is 30th December. Try to arrange to see your doctor as soon as possible.

  • By Betty (not verified) on 11 May 2018 - 22:39

    The first day of my LMP was April 2 I took a pregnancy test at home it's positive, no mornings sickness no brown discharge I only feel crampe almost every day. Is it possible that I might be pregnant?

  • By Midwife @Tommys on 14 May 2018 - 11:31

    Hello Betty, Yes, if your pregnancy test is positive you are pregnant. Please arrange to see your doctor when you can. Very glad that you have located our website and can read about having a safe and healthy pregnancy. Take care

  • By alayo (not verified) on 9 May 2018 - 20:34

    lmp is 18th of february.how old is my pregnancy

  • By Midwife @Tommys on 10 May 2018 - 14:09

    Hi Alayo
    Using your LMP of 18th Feb, and presuming you have a cycle of around 28 days, the most pregnant you can be in 11-12 weeks.
    Congratulations! If you need anymore help or advice, please do get in touch via email - [email protected]
    Sophie,Tommy's Midwife

  • By Roxana (not verified) on 9 May 2018 - 09:55

    I am 31 yrs old and i think I am 5 weeks pregnant. I worried that I have not started folic acid before being pregnant and have started only a week ago. i have vit b12 deficiency and not on any kind of pills. should i take more supplements of folic acid ? i am concerned about neural defects and its my first pregnancy.

  • By Midwife @Tommys on 10 May 2018 - 14:13

    Hi Roxana
    Taking folic acid and pregnancy vitamins both pre- pregnancy and in early pregnancy is the ideal. So as you are already doing this, you do not need to be concerned. Please see the page below for more in depth information from another of our webpages...
    https://www.tommys.org/pregnancy-information/im-pregnant/nutrition-pregnancy/supplements-pregnancy/folic-acid-pregnancy
    Look after yourself and feel free to contact us by phone or email if you need any further advice or assistance.
    Sophie,Tommy's Midwife

  • By Bela (not verified) on 8 May 2018 - 12:24

    Hi, my last period was 20th March and I had intercourse on the 6th of April, I'm about 6 weeks pregnant and already heard my baby's heart beat, I'm a little worried however because I sometimes experience minor twinges, period like cramps, and uncomfortable, I also noticed that I have a very minor brown like discharge when i wipe after peeing, my pee is normal color but this discharge worries me a bit my appointment is on the 29th of May, but is there any cause for concern? Sometimes I get so paranoid of a miscarriage

  • By Midwife @Tommys on 10 May 2018 - 14:26

    Hi Bela
    It is normal for you to feel anxious in your first pregnancy. And it is also sensible to be aware of your symptoms, which you are- and this is great.
    Any abdominal pain or cramps or vaginal bleeding/spotting, at any gestation of pregnancy, ideally should be reviewed to ensure that everything is ok. You can go to your GP who can refer you to an early pregnancy assessment unit before 12 weeks gestation. If you develop severe abdo pain, or the bleeding were to be very heavy, then you must go straight to a&e.
    It is always best to get these things checked out, mostly for your own peace of mind.
    Please feel free to get in touch via email next time [email protected]
    All the best
    Sophie Tommy's Midwife

  • By Bailey (not verified) on 3 May 2018 - 20:44

    Hello! I had unprotected sex on April 12. I was on birth control but only for a short amount of time (a couple weeks) I started my period April 1st and ended April 10 (it was longer because of my new birth control). I have never tracked my period and I didn't try to have a baby. I toke a test about 2 weeks after sex and came back negative. It is May 3rd today and I still haven't gotten my period, what should I do?

  • By Midwife @Tommys on 4 May 2018 - 09:52

    HI - Thank you for your message.
    You haven't shared how regular your periods normally are - bur if your period is late, then it is important you take another pregnancy test. The previous test you took 2 weeks after you has unprotected sex may have been to early. If you are worried or unsure, please contact your GP for further advice.

  • By jasmine (not verified) on 3 May 2018 - 17:20

    ive recently found out im pregnant my last period was round about 26th 27th march how far would that make me roughly

  • By Midwife @Tommys on 4 May 2018 - 09:42

    Hi - Thank you for your message.
    Congratulations on your pregnancy!
    if the first day of your last menstrual period (LMP) was 26/03/2018 - that would make you today (04/05) 5 weeks and 4 days pregnant, with your baby's estimated due date (EDD) as 01/01/2019 - so possibly a new years baby!
    Hope that helps.

  • By Aj (not verified) on 30 Apr 2018 - 21:45

    I have never been pregnant before I missed my period this month and have taken two home pregnancy test which both came out positive! My last period ended the first week of April but normally starts on the 28 of each month. I was wondering how far along I would be now?

  • By Midwife @Tommys on 3 May 2018 - 11:33

    Hi Aj, Congratulations on your Pregnancy!

    When dating a pregnancy, we always go by the first day of your last period. If this was around the 28th March, then you are around 5 weeks pregnant, giving you an estimated due date of 31st December 2018. Hope that this helps, make sure that you are taking your pregnancy multi vitamins and eating healthy. Take Care, Tommy's Midwives x

  • By Taylor (not verified) on 26 Apr 2018 - 22:44

    hi all

    so today I found out I am pregnant. mahoosive shock as I have been off all forms of contraception since 2016 and me and my husband just let things go and see what happens. we haven't been actively trying to conceive but hoping it would happen.
    I have always had funky periods ( every 2 to 3 weeks, lasting between 3 and 5 days) totally random. as I can't be sure when I conceived I politely asked my doctor to put me in for a scan so we can be sure and find out.. he was very reluctant and said I'm being paranoid and I have now for to wait another 2 to 3 weeks before moving forward. I currently have ongoing health issues and right now I am not in the right frame of mind to even tho m about more children. I have a very active 4 year old and although me and my husband are not trying, I really want to see how far gone I am so we can prepare and be organised. am I able to contact the hospital off my own back for an emergency scan or even call my doctors to refer it through asap. as a suffered of severe anxiety and hemiplegic migraines.. I really cannot wait any longer for this..especially over the weekend. it will just eat away at me.

  • By Midwife @Tommys on 27 Apr 2018 - 09:25

    Hi - Thank you for your message. An unexpected pregnancy can cause all kinds of different emotions and concerns, you are not alone!
    You haven't mentioned how many weeks pregnant you are, so advice at this stage is a little limited. Generally your GP refers you for an early pregnancy scan if they feel it is necessary and depending on how many weeks pregnant you think you are - its worth contacting your GP and higlighting your concerns and ongoing health issues to request a referral. Alternatively, some Early Pregnancy Units offer self-referral - which maybe an option if you have concerns. You can find details of Early Pregnancy Units on the following link
    http://www.aepu.org.uk/find-a-unit/

  • By Sarah (not verified) on 25 Apr 2018 - 19:09

    Hi last period was 21/03/2018. I only had unprotected sex 7/04/18. 4 test later found out i was pregnant 25/04/18. When will i be due??

  • By Midwife @Tommys on 27 Apr 2018 - 10:00

    Hi - Thank you for message.
    The first day of your Last Menstrual Period (LMP) is used in early pregnancy to determine how many week pregnant you maybe and your Estimated Due Date (EDD). According to your LMP of 21/03/2018 you were around 5 weeks pregnant on 25/04/2018 when you found out and your baby is due around 25/12/2018.
    Ultrasound scans in early pregnancy are used for dating pregnancies and your EDD can sometimes be adjusted after a scan.

  • By Dee (not verified) on 24 Apr 2018 - 04:30

    I haven't had a period since Feb 12th and that was just spotting. I'm on birth control. I have had a unprotected sex. It feels weird to lay on my stomach. My stomach sometimes rumbles. I am now urinating more frequently. My bowel movement has changed. I was once constipated. Took 3 prego test since last period says negative. What should I do?

  • By Midwife @Tommys on 26 Apr 2018 - 14:37

    Hi Dee, Thank you for your comment.
    It would be advisable for you to go and see your GP if you have stopped having periods and think that you may be pregnant while taking birth control. There is a possibility of women getting pregnant while taking birth control so please go and see your GP, they will be able to do a blood test to check for the pregnancy hormone as this is more sensitive then the urine pregnancy test. Hope this helps, Take Care, Tommy's Midwives x

  • By Stacy (not verified) on 22 Apr 2018 - 13:45

    My last period was on the 15th of March. April 18th I found out that I was pregnant. When should I be expecting my baby?

  • By Midwife @Tommys on 23 Apr 2018 - 15:03

    Estimated due date would be 21st December but scans may give a more accurate date.

  • By Mrs Joseph (not verified) on 24 Apr 2018 - 18:22

    my last period was 7 of March and I found out I was pregnant on the 4 of April how long am I and when is my due date

  • By Midwife @Tommys on 27 Apr 2018 - 11:26

    Hi - Thank you for your message. If the first day of your last menstrual period (LMP) was the 07/03/2018 - then you are 7 weeks and 2 days pregnant today, with your estimated due date (EDD) around 10/12/2018.
    You can use our pregnancy calculator https://www.tommys.org/pregnancy-information/im-pregnant/use-our-pregnancy-calculator-find-out-your-due-date and sign up to follow our week-by-week pregnancy information.

  • By Jules (not verified) on 24 Apr 2018 - 06:42

    Hi Stacy, is that your first day of your last menses? If it is, your Estimated Delivery Date (EDD) will be 20th December.

  • By Judy (not verified) on 19 Apr 2018 - 07:35

    My granddaughter started her last period on Feb. 19 when would her due date be? And how many weeks is she now?

  • By Midwife @Tommys on 19 Apr 2018 - 16:25

    Hi, Thank you for your comment.

    If her last period was the 19th feb then she would be due around the 24th November 2018, this would make her around 8 weeks and 2 days. We would suggest that she goes to the GP and inform them of her pregnancy if she hasn't already, then she can be referred to the midwife for her antenatal care. Hope this helps, Take care, Tommy's Midwives x

  • By Anonymous (not verified) on 25 Apr 2018 - 01:48

    My last period was feb 12 and my due date is December 2nd. So hers should be somewhere in there

  • By Delma (not verified) on 17 Apr 2018 - 22:08

    Hi,

    I missed my period April 5th 2018. it is about to be 2 weeks since my missed period and still no sign of menstrual cycle. I am having nausea, headache and cramping with back pain.
    I have done 2 HCG tests 1 in home test and another at Lab, both negative.
    I am scheduled to come in to do a blood pregnancy test.
    Can I be pregnant? is it too early to show?

  • By Midwife @Tommys on 18 Apr 2018 - 16:47

    Hi Delma
    It is possible that you are pregnant, and using your Last menstrual Period date of April 5th, you are only approx 1-2 weeks pregnant today on the 18th April, so it is unlikely that the urine pregnancy test is good enough to show a positive result. But the blood test should be able to detect it. Sophie, Tommy's Midwife

  • By Louise (not verified) on 10 Apr 2018 - 12:11

    Hello
    I've been on the pill for 10 years and had my withdrawal bleed on 6th March for 6 days and started to take my pill again on 12th March. Myself and my OH decided to TTC and I stopped taking my pill on 19th March which would of been when I ovulated on a calculator I have but unsure as I stopped the pill the day before. We had unprotected sex all that week and I got a withdrawal bleed for 3 days on the 24th March. I got egg white sticky discharge that I have never seen before. My cycle was always 28 days on the pill so I should of had my period 3rd April but no sign and it's been a week now. Been feeling very emotional, tiered and lack of energy. I done a HPT on 8th April but negative. Could I still be pregnant?

    Thank you

  • By Midwife @Tommys on 10 Apr 2018 - 15:01

    Hi Louise
    Yes, it is possible for you yo be pregnant but it not yet be showing on the home pregnancy test as they do not always pick up very low pregnancy HCG readings in the early days and weeks of pregnancy. Give it another week and test again if you have not seen your period. If after 3 weeks of no period, and negative pregnancy tests, then it would be sensible to go to your GP for a review. Often coming off the pill can interrupt your cycle - it can take a full year for your cycle to settle down and return to normal after coming off the pill after taking it for a number of years. Please feel free to call us on 0800 0147800 if you need to talk anything through.
    All the best
    Sophie, Tommy's Midwife

  • By Crystal (not verified) on 8 Apr 2018 - 05:52

    I am seeing my doctor really soon but I am not sure when I might have conceived. I got a positive home test on the 4th of this month. I looked up dates etc and it seems I would have conceived around March 26th. About how far along do you think I'd be?

  • By Midwife @Tommys on 10 Apr 2018 - 09:09

    Hi Crystal,
    you will need to know the date of the first day of your last menstrual period and your average length of cycle length in order to work out how many weeks pregnant you are - which will give you information about roughly when you conceived. Sperm can survive in the body for up to around 5 days, so it possible that you conceived anytime during that window.Your first ultrasound scan will also accurately measure your baby and give you an estimated due date. Please see the link below to help you work out roughly when this was. If you need any assistance, please feel free to call us on 0800 0147800.


    https://www.tommys.org/pregnancy-information/im-pregnant/use-our-pregnancy-calculator-find-out-your-due-date

    Take care, Sophie Tommy's Midwife

  • By Lidwina (not verified) on 6 Apr 2018 - 16:08

    Hi,

    I am 36 yrs old and having one test pack and one lab test, positive pregnant. In week 5 of ultrasound nothing seen, the pregnancy sac was empty, and normal said my doctor. Then at week 7 I there' s a slight of brown blood, and when I wiped 3 times when I peed, it smelt fresh blood, but none at evening. And when I went to my doc to consult about it, I got transvaginal ultrasound and at 7 week pregnant, my pregnancy sac is still empty. My doc told me, he was afraid that probably my pregnancy is blighted, and asked me to wait for 2 more weeks, to wait whether it will naturally bleeding itself, or if not I have to comeback to him. But I still have pregnancy symptomps : nausea, and hungrier more than before I am pregnant. Do you think I have blighted pregnancy?thank you

  • By Midwife @Tommys on 6 Apr 2018 - 16:31

    Hi,
    I am sorry to hear that you are having a difficult and unknown time with this pregnancy. If they are unable to view anything in the pregnancy sac by 7 weeks it does, I am afraid, sound like a blighted ovum. As per guidelines, your doctor will review you in two weeks with another scan to be sure of this diagnosis. It is common to continue to have pregnancy symptoms as your pregnancy hormone is still raised which will be causing the symptoms. I understand this is a very difficult time for you, and waiting for your next scan may feel like a long time. If we can support you at all then please do contact us via [email protected]
    Take care, Tommy's midwife x

  • By Lady (not verified) on 6 Apr 2018 - 02:51

    Hello,
    My LMP started on the 4/2/18...how old could my baby be now and when should I expect him/her...and oh is there nothing I can do to stop throwing up? Its killing me! Lol..thanks

  • By Midwife @Tommys on 6 Apr 2018 - 12:02

    Hi,
    According to your LMP your due date would be about the 11th of November, however when you have your scan at about 11-14 weeks, this will give you your official date which will be used for the rest of the pregnancy. This would make you about 8 weeks and 5 days pregnant today.
    Sorry to hear that you are being so unwell and throwing up, if you are unable to keep any food or water down then do speak with your GP for support and any anti sickness medication that maybe appropriate. Otherwise, if you can, just have sips of water and light snacks throughout the day and rest where you can.
    Best wishes, Tommy's midwives

  • By Jaspreet Kaur (not verified) on 4 Apr 2018 - 15:54

    Hi
    My LP is 27th February 2018.I am pregnant.How many weeks are my now?

  • By Midwife @Tommys on 6 Apr 2018 - 11:57

    Hi Jaspreet,
    According to the date you have given as your LMP, if you have a regular 28 day cycle then you are about 5 weeks and 3 days pregnant today. When you have your dating scan at about 11-14 weeks then this will give you your official due date.
    Best wishes, Tommy's midwives

  • By Jennifer Keeler (not verified) on 3 Apr 2018 - 15:12

    I normally have a 28-32 day cycle with a 4-5 day period (all month depending), this month I was 4 days late and my period only lasted 2 days. Combined with a lower back ache whichnis worse in the mornings and non-existant the rest of the day and constant bloating...could there be a chance I am pregnant?

  • By Midwife @Tommys on 3 Apr 2018 - 16:14

    Hi Jennifer.
    If you have had unprotected intercourse, then it is entirely possible you could be pregnant.
    Although lower back pain and bloating are also common during your monthly cycle, it is also worth noting when this is different for you. Any cycle changes are worth investigating with your doctor, and if there is any concern , you can be referred to gynae outpatients for a review if you are not pregnant.
    All the best and feel free to get in touch privately via email [email protected] or call us on 08000147800
    Sophie,Tommy's Midwife

  • By Marta (not verified) on 2 Apr 2018 - 06:51

    I took my iud on 21 of February and I got my perio6a week later and now as 04/01/18 I'm pregnant. My question is how many weeks pregnant I'm i?

  • By Midwife @Tommys on 3 Apr 2018 - 16:08

    Hi Marta
    The most pregnant you could be, using the dates of your IUD being removed is 4-5 weeks pregnant. But this may change when you attend your first scan as it will go by the measurements of your baby.
    If you need any further information, please feel free to email us privately on [email protected] or call us on 0800 0147800
    All the best
    Sophie,Tommy's Midwife

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