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. 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

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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  • By Parvin (not verified) on 19 Sep 2018 - 12:33

    Hi I started my period last month 15th August since then I haven't started my period I did have unprotected sex with my husband few time and do pregnancy test it still shows negitive I contact my gp and they said to wait but I did have few miscarriage and ectopic pregnancy in the past and was with the hospital miscarriage specialist but no longer with them they did say I have chance to be pregnant and now I am not starting my period still shows negitive my body is changing too. So what do i do now. Thank you

  • By Midwife @Tommys on 21 Sep 2018 - 11:25

    Hi Parvin, If you are planning a pregnancy, what about trying our new pregnancy tool.
    This is a simple way to see if there are any lifestyle changes you could make to help you to conceive and maintain a healthy pregnancy.
    If you have repeated negative pregnancy tests it is extremely unlikely that you are pregnant at this time although I agree with your GP that it is still very early and if you ovulated late your period may still come any day. Take care.

  • By Anonymous (not verified) on 19 Sep 2018 - 04:48

    Every app asks when was the last menstrual cycle, honestly I'm too sure, the day of intercourse was July 28th. How am I supposed to calculate due date?

  • By Midwife @Tommys on 20 Sep 2018 - 15:04

    Hi Thank you for your comment.
    The app should be asking for the first date of your last period, so this should be around 14 days before ovulation. If you are unsure of your dates then we would suggest that you see your GP who can refer you for a dating scan to see how many weeks your are. Hope this helps, Tommy's Midwives x

  • By Pau (not verified) on 18 Sep 2018 - 15:10

    Would like to ask on August 17, 2018 my partner and i didnt have sex but just fooled around he didnt came inside me and just came near my right leg and nearly in my vagina. After that I had my heavy period - 6 days on august 21,2018. My next period should be today, Sept 18,2018 but didnt have it, my boobs are sore and I have cramps and lower back pains, I tried pregnancy test 1 day before my period it was negative, but today been waiting for my period to come but it didnt am I pregnant?

  • By Midwife @Tommys on 20 Sep 2018 - 14:18

    Hi Pau, Thank you for your comment.
    It is unlikely that you are pregnant as you had a heavy period after this incident happened and then you have had negative pregnancy tests. It sounds like your period is a little late this cycle. If you are still worried and your period doesn't come then take another pregnancy test and if it is still negative please see your GP who can do a blood test to check for the pregnancy hormone. Take Care Tommy's Midwives x

  • By Carol (not verified) on 18 Sep 2018 - 09:56

    LMP was on 24,25,26 many weeks am i?

  • By Midwife @Tommys on 20 Sep 2018 - 14:07

    Hi Carol, Thank you for your comment.
    If your LMP was the 24th March then you should be around 26 weeks now. If you have any concerns then please contact your GP or midwife who will be able to advice your further. Take Care, Tommy's Midwives x

  • By Melissa (not verified) on 13 Sep 2018 - 21:37

    My last period was 2nd August 2018 and I had a positive pregnancy test 2 weeks ago. I have had symptoms on and off, sore boobs, cramps, pulling sensation, stitch feeling. I am nervous when the pains are there that things are going wrong but then when they stop I get nervous until they start again. Is that all normal, should I be feeling things on and off? Thanks x

  • By Midwife @Tommys on 14 Sep 2018 - 11:47

    Hi Melissa,
    It is very normal for symptoms to vary, they can be different for each woman, each pregnancy and throughout the pregnancy. Feeling sore boobs and having some mild cramps are very common early pregnancy symptoms. If you find that the cramps are painful or if you have any bleeding then I would advise for you to see your GP just to make sure everything is ok with the pregnancy.
    Best wishes
    Tommy's midwife

  • By brittany (not verified) on 11 Sep 2018 - 01:30

    help, I'm pregnant and I don't know how to tell the father, I'm worried he'll leave me. I have no parents or family so im totally on my own. my bank account is dry to I cant afford health services. What do I do?

  • By Midwife @Tommys on 12 Sep 2018 - 15:05

    Hi Brittany
    This is a public website. Maternity care is free via the NHS in the UK and benefits are available if you need financial support.
    Please can you contact Tommy's Pregnancy Line on 0800 0147 800 or email [email protected] with more information about your situation so that we can give you more personal advice and support.

    Take care
    Tommy's Midwife

  • By Dgold (not verified) on 6 Sep 2018 - 12:18

    The last day of my period was July 21 2018. I just took a pregnancy test a week ago and it was positive. How many weeks am I?

  • By Midwife @Tommys on 11 Sep 2018 - 15:06

    I have calculated that you are 7 weeks and 3 days today (11/09/18)-the baby's due date is 27/04/2019.
    Please contact your GP or local maternity unit so that you be referred to them and start your antenatal care as soon as possible

  • By Jazmin (not verified) on 6 Sep 2018 - 05:09

    I had light spottings a few weeks ago followed by cramps, headache, dizziness, constipation, bloating and fatigue. I did a pregnancy test more than once and they were all negative. What should i do ? I am worried.

  • By Midwife @Tommys on 11 Sep 2018 - 14:59

    I would advise that you discuss your symptoms with your GP if you are still concerned-these symptoms could be due to several causes.

  • By thembi (not verified) on 4 Sep 2018 - 21:19

    i go for 24 menstrual cycle and yet since ive been trying to get pregnant but no luck i wanna know when would i try again ..please Help

  • By Midwife @Tommys on 11 Sep 2018 - 10:33

    Thank you for you comment.
    Your cycle starts on the first day of your period and continues up to the first day of your next period.
    Conception occurs around the time that you ovulate-this is usually 10-16 days before your next period.
    To boost your chances of conceiving, aim to have regular sex (every 2 to 3 days) throughout your cycle so you know that there should hopefully be good-quality sperm waiting when the egg is released. An active sex life is all most people need to conceive.
    I have attached a link with more information for you

    Tommy's Midwife

  • By Lily (not verified) on 1 Sep 2018 - 13:22

    Hi.. The last time I had intercourse was on May 3rd and I had normal period 3 months after that until last month my period lasted shorter than usual.. and for this month my period has been late for 3 days. I took a pregnancy test on August 13 and it came out negative. Is it possible that I’m pregnant?

  • By Midwife @Tommys on 7 Sep 2018 - 15:02

    Hi Lily,
    It does not sound like you are pregnant as you have had a negative test and periods since you last had intercourse. If you have concerns about your cycle then do see your GP.
    Best wishes
    Tommy's midwife

  • By Kaylyn (not verified) on 10 Sep 2018 - 04:48

    Me and my BF have had sex my last period stopped on 8/16/17 and I confirmed the pregnancy on 9/9/17 when would my due date be

  • By Midwife @Tommys on 12 Sep 2018 - 12:40

    Your estimated due date is 23/05/2019-this is calculated according the date your period ended (Due date is usually calculated from the 1st day of your last period) and assuming you have a 28 day cycle.
    Please contact your GP or maternity unit to be referred for antenatal care

  • By hp (not verified) on 11 Sep 2018 - 01:28


  • By Swethasri (not verified) on 28 Aug 2018 - 05:45

    My last period was on 21.07.18. Pregnancy test done on 24.08.18. So, I want to know this week is which week

  • By Midwife @Tommys on 29 Aug 2018 - 12:36

    Hi Swethasri
    Using your last menstrual period date of 21/7/18 and presuming you have a 28 day cycle, you will between roughly 5 to 6 weeks pregnant. You should see your doctor for referral to maternity services and for your first ultrasound scan to be booked in.
    All the best
    Tommy's Midwife

  • By Anon (not verified) on 25 Aug 2018 - 19:30

    I have a nearly 4 year old. Since then had 3 Miscarriages - one early and 2 missed miscarriages. They couldn’t find a reason apart from putting it down to me being diagnosed with Graves Disease after the miscarriages. I’m now nearly 6 weeks and GP doesn’t seem to care or to monitor me. Midwives won’t see me until 8 weeks. My Endocrinologist can only keep an eye on my thyroid levels and he said I won’t be entitled to any extra scans. I feel I am not supported or monitored enough.

  • By Midwife @Tommys on 29 Aug 2018 - 10:53

    I am sorry that you are not feeling well supported. I know this is very difficult, but there is not usually a lot of support available in the first 8 weeks of pregnancy. The midwives cannot offer you a booking apt until 8 weeks at the earliest and there is no real checks that the GP could do to check on the pregnancy before 16 weeks. The only way to check you, is for you to be referred to your local early pregnancy assessment unit. You will need to be referred by your GP to be seen there. At the early pregnancy clinic, they may offer you a trans-vaginal scan , as it is too early for an abdominal scan. They would only offer you a blood test if there is concern about the growth of the fetus at trans-vaginal scan or if you have had some bleeding. I know it is very difficult in these early weeks. Due to your history of x3 miscarriages though, you should be offered reassurance scans in the early pregnancy assessment unit, so please do get your GP to make the referral asap for you. If you have any further questions - please call or email us as this part of the website is not manned in the same way as our midwife email or phoneline. All the best - Tommy's Midwife

  • By Amanda (not verified) on 25 Aug 2018 - 08:11

    Please help me, I have my last period on 11th July 2018, since then I have not seen it again, but I feel tired every morning, could it possible that I'm pregnant and how many weeks pregnant please

  • By Midwife @Tommys on 29 Aug 2018 - 10:44

    Hi Amanda
    You need to do a pregnancy test to be sure one way or another. If you have been having unprotected sex, then it is possible that you might be pregnant.
    If you are pregnant, then the most you would be is 7 weeks pregnant now according to your last period date, so this would certainly show up on a pregnancy test.
    If the pregnancy test is negative and you have still not seen a period, it is important that you go to your GP as you may need referral to a gynaecology clinic.
    All the best
    Tommy's Midwife

  • By Joy (not verified) on 20 Aug 2018 - 21:37

    My last period was 5th may had sex with my hubby 25th May. I've not seen my period since then . Is it possible I'm pregnant . I'm yet to do pregnancy test.

  • By Midwife @Tommys on 21 Aug 2018 - 16:09

    Hi Joy,
    If you are having unprotected sex and you have not had a period since May 5th you could be pregnant. Please do a pregnancy test today.
    If you are worried or need any further advice email us at [email protected]
    Warm wishes
    Anna-Tommy's Midwife

  • By Katso maila (not verified) on 7 Sep 2018 - 18:46

    My last period was on the 9 September till the 11 September ,after that I have sex with my man.and 2 day I had my menstruation with clod but was not much and it's stopped. I did the pregnancy test said negative .am i pregnant?

  • By Midwife @Tommys on 11 Sep 2018 - 16:49

    I would suggest repeating the pregnancy test if you think you might be pregnant-sometimes the hormone levels have not yet risen enough to give a positive result. If it is positive please contact your GP or maternity unit for a referral to start your antenatal care.
    I have attached a link with more information for you-

    Tommy's Midwife

  • By Lina (not verified) on 13 Aug 2018 - 03:41

    Had irregular periods as well diagnosed by a gynecologist I had polycystic ovaries, my last period was may 29 2018 so uhm this was a really unexpected and not sure what to do next or how to proceed with this....

  • By Midwife @Tommys on 13 Aug 2018 - 16:13

    Congratulation on your pregnancy. Please don't worry, Make an appointment to see your doctor and he/she will guide you to the next steps. And you can read all about it on our site.

  • By Rebecca (not verified) on 11 Aug 2018 - 18:14

    I am 7 weeks pregnant and I have some symptoms but not peeing a lot I am worried that something is wrong

  • By Midwife @Tommys on 13 Aug 2018 - 16:11

    Hi Rebecca, There is no reason to be concerned. Make sure that you are drinking plenty of water and this will increase your fluid output. Many women have no symptoms in early pregnancy and it is quite normal. Take care

  • By Pankaja (not verified) on 9 Aug 2018 - 08:42

    My last peried date is 22/06/2018 I confirmed pregnancy on 3/8/2018

  • By Midwife @Tommys on 13 Aug 2018 - 16:09

    With these dates your due date will be March 28th 2019. Best wishes

  • By Lawrenta okunrobo (not verified) on 17 Aug 2018 - 12:27

    My last period date is 29/6/2018 i confirmed pregnancy on the 7/8/2018

  • By Midwife @Tommys on 17 Aug 2018 - 12:50

    Hi - If the date of the first day bleeding in your last menstrual period (LMP) was 29/06/2018 you are 11+2 days pregnant and your estimated due date (EDD) would be around 05/04/2019.

  • By emelda (not verified) on 6 Aug 2018 - 22:37

    I had periods two times in June. The Last was on the 28th and the doctor confirmed that I'm pregnant. How far am I now?

  • By Midwife @Tommys on 8 Aug 2018 - 16:05

    Hi Emelda
    Using your LMP of 28th June, you would be approx 5-6 weeks pregnant today.
    They will give you an accurate gestation and due date at your 12 week scan.
    All the best
    Tommy's Midwife

  • By Diana Gheorghiu (not verified) on 8 Sep 2018 - 13:17

    You have bleeding one week after you get pregnant. You should be like 10 weeks

  • By Adriana (not verified) on 2 Aug 2018 - 03:59

    I just found out I’m pregnant!:)
    My last period was June 26-30.
    I found out I was pregnant July 30th. I have yet to see my midwife but I’d like to know how many weeks am I ? Thank you :)

  • By Midwife @Tommys on 3 Aug 2018 - 13:09

    Dear Adriana,
    According to your date you are about 5 weeks and 2 days pregnant, this is based on you having a regular 28 day cycle. You can also use our calculator too:
    In case you are not already, then do start taking a folic acid supplement.
    Best wishes
    Tommy's midwife

  • By Roshan (not verified) on 20 Aug 2018 - 20:35

    I am also expecting pregnancy. Somewhere inside me I feel that I am pregnant. I have stomach ache. Sometimes like cramps. Sometimes near to belly button or around belly button. I am feeling puking. But tiredness is there. I had my periods on Jul 26th. When is that I can check my pregnancy. What all I should do to be safe until I find I am pregnant. Everyone pls pray for me. I really need a baby. I don't want my periods this month and coming next 9 months. Pls keep me in your prayers.

  • By Roshan (not verified) on 20 Aug 2018 - 20:36

    I am also expecting pregnancy. Somewhere inside me I feel that I am pregnant. I have stomach ache. Sometimes like cramps. Sometimes near to belly button or around belly button. I am feeling puking. But tiredness is there. I had my periods on Jul 26th. When is that I can check my pregnancy. What all I should do to be safe until I find I am pregnant. Everyone pls pray for me. I really need a baby. I don't want my periods this month and coming next 9 months. Pls keep me in your prayers.

  • By Midwife @Tommys on 21 Aug 2018 - 16:03

    Hi Roshan,
    if your periods are regular you could do a pregnancy test on August 22nd.
    I am thinking of you and hope very much that it is good news this month.
    Warmest wishes
    Anna-Tommy's Midwife

  • By ?? (not verified) on 28 Jul 2018 - 06:09

    Hi I’m 6 weeks and 6 days pregnant, I miss carried in 2013 at nearly 12 weeks but now I’m worried because I have hardly any if at all any discharge! Is this normal?

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