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

Sources

NHS Choices. Your pregnancy week by week http://www.nhs.uk/conditions/pregnancy-and-baby/pages/pregnancy-week-by-week.aspx#close (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 http://publications.nice.org.uk/antenatal-care-cg62

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

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Comments

  • By Nadine (not verified) on 18 Jul 2018 - 19:15

    So I have been infertile for over 10years due to complications from the birth of my 3 child.
    Mainly I had blocked tubes. 2 years ago I fell pregnant, miscarried at 6 weeks, I went on to have another 6 pregnancies all miscarried at around 6 weeks.
    I am pregnant again I am on progesterone pessaries. My HCG was 14 and progesterone was 48 now my HCG is 30 and progesterone has fallen to 26. Tests are 48 hours apart.
    I don’t know how many more times I can do this! I don’t see the doctor until next week for more tests. Normally they give me levels then tell me there’s nothing more they can do, then they hang up and I’m left to just deal with it alone.

  • By Midwife @Tommys on 19 Jul 2018 - 13:30

    Hi Nadine, Thank you for your comment.

    We are so sorry to hear about your miscarriages, we cannot even begin to imagine what you must be going through at this time. As you have had more then 3 reoccurring miscarriages you can be referred to one of the Tommy's Miscarriage clinics. If you go to this link it will tell you your nearest Tommy's Miscarriage clinic and how to get a referral from your GP https://www.tommys.org/our-organisation/help-and-support/clinical-trials
    If you make an appointment with your GP they will be able to refer you so that you can be seen by one of the specialists. If you need any further support or have any questions then please email on [email protected] Hope this helps, Take Care, Tommy's Midwives x

  • By Nadine (not verified) on 19 Jul 2018 - 20:10

    Thank you for your reply.
    I do not meet your criteria to come to 1 of the centres. I am 38 years old from wales and my miscarriages have been early miscarriages. I have looked at all the criteria’s for different centres but I don’t come under any of them, unfortunately. I’m just going to be another lady going through this that doesn’t get any support until 1 day I might meet the right criteria.

  • By Sindhu Siva (not verified) on 12 Jul 2018 - 03:44

    My last period was on 30May2018. Urine pregnancy showed positive. Yesterday (11Aug2018) visited doctor and early pregnancy scan was done(trans vaginal scan). Not foetal pole/ yolk sac noted(exact term as given in the report) but sac measuring 0.3cm seen in endometrium. Doc suggested blood hcg test and yet to get the results. During initial days faint line was noted in upt, yesterday evening and today morning I repeated upt at home and got strong positive. I am worried please help me.

  • By Midwife @Tommys on 12 Jul 2018 - 16:11

    Hi Sindhu,
    I am sorry to hear that you are experiencing a confusing time in this pregnancy. It is difficult to know what is happening at the moment, I am afraid I am unable to say. HCG monitoring will showing if the levels are falling or rising helping to give a better idea if the pregnancy is continuing and they should also offer you a repeat scan, usually in two weeks time. It is difficult to be in limbo at the moment, please look after yourself and use the support you have around you.
    Best wishes
    Tommy's midwife

  • By Sindhu Siva (not verified) on 12 Jul 2018 - 18:46

    Thanks for the reply:-)

  • By krp (not verified) on 12 Jul 2018 - 03:37

    My last period was June 16th. Had intercourse on June 27-28. Tested positive today 7/11.

  • By krp (not verified) on 12 Jul 2018 - 17:34

    when is my due date

  • By Midwife @Tommys on 13 Jul 2018 - 13:38

    Hi,
    You have not provided any dates therefore I am unable to advise when your baby is due, you can use our calculator to work out your dates if this helps: https://www.tommys.org/pregnancy-information/im-pregnant/use-our-pregnancy-calculator-find-out-your-due-date
    Best wishes
    Tommy's midwife

  • By Amal (not verified) on 7 Jul 2018 - 07:07

    Hi,

    my LMP was 25/5/2018 i tested both blood and urine and it was positive I recently did an u/s and the DR said there was no Foetal pole, he said come back again after 2 weeks for another U/s your pregnancy is positive but can't see now
    so when i should go whats my pregnancy weeks dua date

  • By Midwife @Tommys on 9 Jul 2018 - 15:50

    It is best to wait for the next USS before trying to date your pregnancy. Sometimes the pregnancy doesn't develop as expected and sometimes the dates are incorrect. Until your next USS it isn't possible to know what is happening.

  • By Christine (not verified) on 5 Jul 2018 - 09:07

    I had my periods 2 times in may Dat was at the beginning of May and the second one on 19-21 may. I didn't see my periods in June, I tested positive on 30th june

  • By Midwife @Tommys on 5 Jul 2018 - 15:34

    Hi Christine, Thank you for your comment and congratulations on your pregnancy.

    If the first day of your last period was around the 19th May then you should be around 6-7 weeks pregnant. Going from the dates that you have given, conception may of occurred at the beginning of June. If you are unsure of your dates then it is advisable to go and see your GP who should be able to refer you for an early dating scan then you will know for sure. Hope this helps, Take Care, Tommy's Midwives x

  • By Amy (not verified) on 4 Jul 2018 - 14:51

    HELP PLZ
    I did a pregnancy test 3 times yesterday 3/7/18 and its positive. But my ladt period was from 6 to 10/6/2018 i didn't have intercourse untill the 17/6/ 2018. How can i be pregnant? and how many weeks am i? am confused because i had an ectopic 2016 November . And am panicking. Help HELP plz

  • By Midwife @Tommys on 4 Jul 2018 - 15:53

    Hi Amy
    Using your last menstrual period date of 6th June, the most pregnant you could be is 4 weeks pregnant today. But if you had intercourse on the 17th June, then you may only be 2-3 weeks pregnant max
    Only an Ultrasound scan can accurately date the pregnancy by correlating your last menstrual period date and the baby's growth.
    Please visit your GP to get your maternity care/ultrasound scan booked and/or to review your options.
    All the best
    Sophie, Tommy's Midwife

  • By Me (not verified) on 4 Jul 2018 - 14:11

    Hi

    I had a miscarriage early this year and went on contraceptives,they treated me badly and I got off them I recently did an u/s and the DR said there was no Foetal pole,she did a round of blood tests and said I must come back again for another U/s m very nervous and needed a second opinion.

  • By Midwife @Tommys on 5 Jul 2018 - 14:13

    Hi, Thank you for your comment.
    It is normal practice that if you are very early in your pregnancy then it can be difficult to see anything on scan as the pregnancy is so small. The Dr is right is asking you to come back in a few days to have another scan, this way they will of given enough time for the pregnancy to have grown, they will expect to see something on the next scan. It can be a nervous wait when you want answers but try and stay calm while you are waiting for your blood results and scan. If you have any concerns then please contact your local early pregnancy unit. Take Care, Tommy's Midwives x

  • By stella obi (not verified) on 4 Jul 2018 - 09:51

    I had sex wit my boyfriend on d 19/04/2018 and my LMP was 12 April pls when is my due date and many weeks pregnant

  • By Midwife @Tommys on 4 Jul 2018 - 16:05

    Using your LMP of May 12th, you would be no more than 10-11 weeks pregnant today. This will be confirmed on ultrasound scan alongside fetal growth.
    All the best
    Sophie,Tommy's Midwife

  • By Anonymous (not verified) on 4 Jul 2018 - 23:04

    tanks ma I appreciate

  • By Mahsa (not verified) on 3 Jul 2018 - 19:42

    Last Period Start Date: May 15
    Ovulation Test: YES on May 26
    Intercourse May 26, 27 and 28
    Tested Positive on June 14

    How many weeks am I now?

  • By Midwife @Tommys on 4 Jul 2018 - 16:03

    Hi Mahsa
    Using your last period date of 15th May and presuming you have a 28 day cycle- your would be approx 7 weeks pregnant today. This might change slightly ( most likely to be a little less far along than that) when you go for your scan allowing for adjustment between fetal growth and your period date.
    All the best
    Sophie,Tommy's Midwife

  • By Neo (not verified) on 3 Jul 2018 - 15:59

    Hi. I last saw my periods on the 17 May. And I had unprotected sex on the 1&2 June and I drank morning after pills on the 3rd but they didn’t work. I was suppose to get my periods on the 11th June but didn’t get them and my boobs started getting tender and heavy so I took a pregnancy test it showed a positive result. So how many weeks am I?

  • By Midwife @Tommys on 4 Jul 2018 - 15:59

    Hi Neo
    using your LMP of 17th May, the most pregnant you could be is approx 7 weeks, but since you can pinpoint when you had intercourse, you are more likely to be around 5 weeks pregnant approx.
    Please visit your GP to book in for your antental care/ultrasound scan/ to review your options.
    All the best
    Sophie,Tommy's Midwife

  • By Pooja (not verified) on 3 Jul 2018 - 15:53

    My last period date was 30 may .today i check and two lines are shown . how many days i am pregnent

  • By Midwife @Tommys on 4 Jul 2018 - 15:55

    Hi Pooja
    Using your last menstrual period of 30/5/18 you are no more than 5 weeks pregnant exactly today.
    Please see your GP to book for maternity care/ultrasound scan or to review your options. Please take care
    Sophie,Tommy's Midwife

  • By Lisa (not verified) on 2 Jul 2018 - 18:38

    5 weeks pregnant and experiencing lower abdominal pain once at night , had ultrasound done internal os closed
    Ps: pain on lower leftside

  • By Midwife @Tommys on 3 Jul 2018 - 13:58

    Hi Lisa,
    I assume that the ultrasongrapher or doctor saw a gestational sac at your scan?
    Mild aches and pains are common in pregnancy. Sharp twinges and pulling or pinching sensations when you move are most likely to be ligament pain (in the pelvic or groin area and either side of belly button). Hormonal changes cause the ligaments which support your organs and growing uterus to soften and stretch.
    Usually change of position, rest and a warm bath or applying a heat pad will help to ease this discomfort. The discomfort should only be mild and occasional. Some women also experience mild cramping pains in pregnancy - this is due to increased congestion of blood in the pelvic region and the release of hormones called prostaglandins - which usually cause period pain during menstruation. Again this pain should only be mild and occasional - and improve with rest and heat. You may be feeling extremely tired or have mild ligament pain - these are also ongoing pregnancy symptoms. Occasionally such symptoms settle or stop early around 8-9 weeks rather than at the end of the first trimester.
    Please keep an eye on the pain if it were to become extremely painful with vaginal bleeding please see your GP, or out of hours call 111 for advice.
    I hope this helps. If you are feeling worried you can always call the midwives on 0800 0147 800
    Warmest wishes
    Anna-Tommy's Midwife

  • By Tash (not verified) on 2 Jul 2018 - 15:50

    My last period started 27th May
    Took a test yesterday but only seeing doctor end of July
    How far could I be right now?

  • By Midwife @Tommys on 2 Jul 2018 - 16:27

    Hi,
    You are 5 weeks now with due date March 3rd 2019.

  • By Jenni (not verified) on 2 Jul 2018 - 10:11

    I did a urine pregnancy test that came out two lines. Pls How many weeks pregnant am I?

  • By Midwife @Tommys on 2 Jul 2018 - 15:37

    You are 5-6 weeks pregnant now with due date 1st March 2019.

  • By Rossi (not verified) on 1 Jul 2018 - 23:41

    I never got my period on April 20th how many weeks I am ?? I took a test on may 9th and it showed positive also can you help me find a good place to go to get a check that doesn't cost alot here ion Scottsdale

  • By Midwife @Tommys on 2 Jul 2018 - 15:34

    With your LMP (last menstrual period) being 20th April you would be about 10 weeks pregnant now. Due date is January 26th 2019. I am afraid I don't know where Scottsdale is so won't be able to help you with arranging your care. If you are in the UK you should go to see your GP.

  • By Rainbow Pregnancy (not verified) on 28 Jun 2018 - 19:52

    Hi - I had my first u/s on Monday where I was supposed to be exactly 6 weeks 0 days and a heart rate of 98 bpm was detected. I had a m/c earlier this year and I am worried that this rate is low. My fertility also said that it is somewhat smaller than 6 weeks although did not comment further. She said there is 50/50 chance of it going wither way. I am just looking for a second opinion and some assurance. I am going back tomorrow for a follow up u/s :)

  • By Midwife @Tommys on 29 Jun 2018 - 11:50

    Hi,
    I am sorry to hear that you have experienced a miscarriage and this pregnancy is seeming very uncertain at the moment. I am afraid it is difficult to know the future of this pregnancy but it is great that you are being followed up and monitored regularly.
    If we can support you then please do be in touch.
    Wishing you all the very best
    Tommy's midwife

  • By hope (not verified) on 23 Jun 2018 - 17:43

    my last period was on 19-22 February 2018

  • By Midwife @Tommys on 25 Jun 2018 - 14:11

    By these dates your pregnancy is now in week 18. Have you visited your doctor or midwife yet?

  • By bethanyallen (not verified) on 22 Jun 2018 - 16:41

    i took a pregnancy test and it came back positive but i dont no roughly how far i am as me and my fiance cant remember when i was on last how can i find out how far i am i dont see the midwife until the 2nd july

  • By Midwife @Tommys on 25 Jun 2018 - 14:09

    Your pregnancy will be dated when you have your scan. This is usually from 11-14 weeks. You will be given a due date at this appointment.

  • By Claire Lim (not verified) on 22 Jun 2018 - 15:11

    Hi,

    I have an irregular period usually delayed for 3-4days and the latest is 3 weeks. My LMP was last April 20th ended 25th and now it's been 2 months and I haven't gotten my period still within the span of those weeks I have been having intercourse. Is it possible that I'm pregnant?

  • By Midwife @Tommys on 22 Jun 2018 - 15:34

    Hi Claire,
    It is possible that you are pregnant however you would need to take a pregnant test to confirm this.
    Best wishes
    Tommy's midwife

  • By Emma (not verified) on 22 Jun 2018 - 13:22

    Hi I ovulated 1-4 June I was due to have a period on the 18th June but I started to bleed on the 14th but only lasted 2 days and I’m normally regular also have been taking tests we have had positive and negative ones I’m confused with what’s happening am I pregnant

  • By Midwife @Tommys on 22 Jun 2018 - 15:32

    Hi Emma,
    It is difficult to know for sure, we do take any positive test as a pregnancy, it could be that the different tests have different sensitivities. We would take it as you are pregnant but it may be useful to see your GP for a blood test to confirm your pregnancy.
    Best wishes
    Tommy's midwife

  • By mmoho (not verified) on 22 Jun 2018 - 02:41

    I slept with my boyfriend in April and the whole of May I didn't see my period but in June I saw them could it be that I'm pregnant im experiencing sudden change in my belly yet I toke a pregnancy test twice but it gives me one line and not two

  • By Midwife @Tommys on 22 Jun 2018 - 15:30

    Hi Mmoho,
    It maybe that it is a little soon to do a pregnancy test, if you had a period in June and had intercourse since then I would advise for you to wait to see if your next period comes, and if not then to take pregnancy test. If you keep having negative tests and your period does not come then do see your GP for a review.
    Best wishes
    Tommy's midwife

  • By Ana (not verified) on 21 Jun 2018 - 07:43

    Hey my period was due on 17 may but i didnt bleeded n i got implantation bleeding about 2 weeks ago and im having morning sickness, a bit nausea, pain in tummy, mood swings and body aching. Is it normal? so how many weeks i could be pregnant ?

  • By Midwife @Tommys on 21 Jun 2018 - 16:39

    Dear Ana,
    I would need the date of the first day of your last period to be able to work out how many weeks pregnant your are. your pregnancy symptoms sound very normal but if you have any pain and/bleeding then do be in contact with your GP for a review.
    Best wishes
    Tommy's midwife

  • By Elsie (not verified) on 20 Jun 2018 - 06:54

    My last period was on 24 February 2018

  • By Midwife @Tommys on 21 Jun 2018 - 16:36

    Dear Elsie,
    From the dates that you have given, if your cycle is 28 days and regular, then your baby will be due about the 1st of December. You will have a dating scan when you are 12 weeks pregnant which will give you your actual due date.
    Best wishes
    Tommy's midwife

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