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 9 months of pregnancy. Click here to sign up.


Pregnant women need expert advice and support at this time

We’ve seen a staggering 72% more demand for urgent support from expectant mums as they struggle to get the advice, community, and emotional support they need.

As Covid-19 leaves the future uncertain, postponed midwife appointments and cancelled antenatal classes have created a worrying set of circumstances for expectant parents. 

Our pioneering research, midwife-led advice and online support is more important than ever: but we’re up against the greatest challenge we’ve ever seen. Add your name to show support.

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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 carol (not verified) on 28 May 2018 - 16:15

      hi,i had the last period between 24th to 26th march.i went for the test and found out that iam many weeks am i?
      when is my due date?

    • By Midwife @Tommys on 29 May 2018 - 11:20

      Hi Carol
      Using your LMP date of lets say 25th March 2018, you could be up to 9 weeks pregnant and your due date would be somewhere around 30th Dec 2018. When you go for your dating scan, they will give you an accurate gestation and due date based on the measurements of the growing baby.
      Sophie,Tommy's Midwife

    • By Jessica (not verified) on 25 May 2018 - 12:05

      Hello, I suffered a miscarriage at 7 weeks in early March, I have had 1 period between and am now 7+2 weeks pregnant again. The fear of having another miscarriage again is awful, this time round I have had more severe symptoms, sore breasts, sickness, nausea, tiredness, I can’t remember having any apart from sore breasts last time, but the past couple of days they seem to have eased so much, my appetite is back, my breasts are fine, I’m not having half any much general achy pains anywhere. I’m not bleeding though, is it normal to have days when you have no symptoms?! X

    • By Midwife @Tommys on 25 May 2018 - 12:28

      Hi Jessica,
      I am sorry to hear that you experienced a miscarriage previously, and pregnancy after a miscarriage is often a time filled with anxiety and worry. It is reassuring that you do not mention that you have any pain or bleeding. Pregnancy symptoms can come and go, and vary throughout the pregnancy and are different for everyone. Commonly they start to reduced towards the end of the first trimester. Having said that, it sounds like you have noted a sudden loss in symptoms, and given your history, I would suggest to call your GP to see if they can refer you to the early pregnancy unit for a review.
      If you would like to talk further you can email us [email protected]
      Best wishes,
      Tommy's midwives

    • By anni (not verified) on 24 May 2018 - 15:37

      Had sex 2days after my period, after two week began expirencing pregnancy signs as, tireness, nausea, feeling sleepy, and some few more which continued till a week
      Making it 3weeks. Den on the forth week, i get some pains in my abdomen and suddenly everything stops, no more signs and no more pregnancy. No bleeding just some vigina white-slippry discharges and pains on my lower back and lower stomach and abit of fever. Its happen 3 times in 3 direct months

    • By Midwife @Tommys on 24 May 2018 - 16:20

      Hi Anni,
      It is difficult to know if you have been pregnant each time or if this is just changes that are occurring in your cycle. Without a pregnancy test we would know for sure. If you have been trying for a pregnancy for longer than a year then do going and see your GP for support. We also advised to be taking folic acid supplement if you are trying for a pregnancy.
      Best wishes, Tommy's midwives

    • By Unknown (not verified) on 24 May 2018 - 08:05

      I had sex on 1/26/18 and missed my period in February but had a period on 3/21 and missed my period again in may but got my last period on may 4th could I be pregnant?

    • By Midwife @Tommys on 24 May 2018 - 16:12

      Hi Layla,
      It is very difficult to know if you are pregnant, you will need to do a pregnancy test to be sure. If you are have intercourse with out protection there is always a chance of pregnancy.
      Best wishes.

    • By Lala (not verified) on 23 May 2018 - 09:44

      I had my LP on the 17th in April and had sex on April 25th with a contraceptive (condom). I had a brown discharge from april 2-5 and gotten another brown discharge on april 10th. I was expecting my period on the 18th of may but I'm 5 days late now. Is it possible that Im pregnant?

    • By Midwife @Tommys on 24 May 2018 - 11:39

      Hi Lala, Thank you for your comment.
      As your period is 5 days late then we would suggest that you do a pregnancy test just to see if you are pregnant. No contraceptive is 100% and occasionally women can fall pregnant when using condoms so for this reason just take a pregnancy test to be sure. Hope this helps, take care, Tommy's Midwives x

    • By Lala (not verified) on 26 May 2018 - 14:14

      Hello! Thank you for your response. I already tried pegnancy test and it shows a negative result. And as of now im already 8 days late. I feel so full,bloated and Im experiencing light cramps. I was thinking that maybe my irregularity just kick in , which happens rarely since I never tried having very late period just like this one. Im really anxious. Thanks

    • By Midwife @Tommys on 29 May 2018 - 11:23

      Hi Lala.
      It might be sensible to repeat the pregnancy test again if you are now 8 days late. Taking the pregnancy test any earlier than a week after your missed period may give you a false negative result.
      If it is negative, then you should go to your GP to be reviewed and if they are concerned, then they may send you for a Gynae outpatient referral.
      All the best
      Sophie,Tommy's Midwife

    • By Lindsay (not verified) on 22 May 2018 - 00:12

      Hi there, I recently just found out I am pregnant but can't remember the last time I had my period. I want to say March 10th but can't be certain. I'm hardly showing any signs of being pregnant other than a hugely increased appetite. I'm not sure what my first steps should be or where to even begin. Any help or suggestions would be greatly appreciated. Thanks.

    • By Midwife @Tommys on 24 May 2018 - 09:39

      Hi Lindsay, Thank you for your comment.

      Congratulations on your pregnancy. If you are unsure of your dates then we would advice that you make an appointment to see your GP who will be able to send you for an early scan and then they will be able to measure the baby and calculate how many weeks pregnant you are. Make sure that you are taking your pregnancy vitamins and maintaining a health diet. Hope this helps, take care, Tommy's Midwives x

    • By Paige (not verified) on 20 May 2018 - 22:11

      I had sex (on birth control) April 8th. I got sick with a throat infection the week of April 30th. And I also had a period during the first week of May during my inactive pills. I haven’t been feeling good and have a loss of appetite. I’m now bleeding again 2 weeks after my period. I did take an antibiotic called cefdinar between period and consistent spotting. Any ideas?

    • By Sandy (not verified) on 19 May 2018 - 18:16

      Hi, I'm 8 weeks preggies & my bump is showing, as if I've passed my trimester. Could it be multiples?
      I'm going for a scan at 12 weeks.

    • By Midwife @Tommys on 21 May 2018 - 15:08

      Hi Sandy, Every woman is different and some women show earlier than others. It is possible that you may be carrying twins but you will have to wait until the scan to find out. Best wishes

    • By Sikuku (not verified) on 18 May 2018 - 20:21

      hi, my LMP was 30/3/2028 at the moment am feeling weak, having a stomach pain on one side (right hand side) and also a time i feel am out of breath after a walk or standing for a long time, is there any problem and kindly confirm me my weeks of pregnancy as at the moment thanks.

    • By Midwife @Tommys on 21 May 2018 - 10:25

      Hi Sikuku, I calculate you are 7 weeks plus 3 days today. If your stomach pains are severe or persistent you should be checked by a doctor or midwife to rule out an ectopic pregnancy. See our information about stomach pain.

    • 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 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...
      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

    • 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 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.

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