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 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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    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 joy (not verified) on 13 Jun 2018 - 10:06

      my lmp was 06/05/2018. and I am pregnant. I am how many weeks pregnant and when is my due date?

    • By Midwife @Tommys on 13 Jun 2018 - 11:59

      Hi Joy
      Using your LMP of 6/5/18 and presuming you have a 28 day cycle. The most pregnant you are is 5 weeks. Your due date would be around 11th Feb 2019
      All the best
      Sophie,Tommy's Midwife

    • By emma (not verified) on 13 Jun 2018 - 09:40

      i had my last period on the 16th may 2o18 and i had intercourse on the 24th may. i have been getting signs. waves of nausea.. gassy reflux.. constipation.. twinges in the lower ab and back.. also i got streps throat the other day out of nowhere.. was the 10th june to early to take a test.. how far along would i be? please help with advice x

    • By Midwife @Tommys on 13 Jun 2018 - 12:38

      Hi Emma
      the best time to do a pregnancy test, is with the first wee of the morning and to wait at least a week after your period is late. In this time, the HCG levels (pregnancy hormones) will have had time to build up in your system. Testing before your period would be due can give a false negative result. So wait until a week after your period is due and test again. Then, the result will be a accurate whether it is negative or positive.
      If you have not seen your period after 1 week, and you have a negative test, please to go to be seen by your GP.
      All the best
      Sophie,Tommy's Midwife

    • By Melissa (not verified) on 13 Jun 2018 - 03:27

      I'm 12 weeks I have fibroids & the pain gets bad at times what can I do to ease the pain

    • By Midwife @Tommys on 13 Jun 2018 - 12:41

      Hi Melissa
      You need to be seen by your Obstetric consultant at the hospital as soon as possible. They will be able to support you and guide you in what to expect with a pregnancy with fibroids.
      All the best
      Sophie,Tommy's Midwife

    • By Bex (not verified) on 11 Jun 2018 - 17:47

      Hi, just looking for advice, I had the implant up until February this year, and had regular periods up until this month I was due on today (11th) but nothing, so I've taken a test and it's negative. What's the best thing to do next? Do I test again tomorrow first thing in the morning or wait a week?
      Thank you. X

    • By Midwife @Tommys on 12 Jun 2018 - 14:27

      Hi Bex,
      Just so that I'm clear, since your implant was removed in February your periods returned to a regular cycle and you should have started your period on the 11th?
      I would repeat the pregnancy test this week if your period doesn't come first. The hormone hCG that the test is sensitive to usually doubles every 48 hours so it would be wise to wait to allow this to happen and also not to spend money on expensive repeat tests.
      Take care and please get back in touch if we can help you
      Anna-Tommy's Midwife

    • By Bex (not verified) on 12 Jun 2018 - 15:16

      Yes, I've had regular periods since having the implant removed.
      Thank you x

    • By grace (not verified) on 11 Jun 2018 - 07:10

      my lmp was 23rd of march 2018

    • By Midwife @Tommys on 11 Jun 2018 - 15:10

      Hi Grace, Your due date is 29th December 2018. Take care x

    • By Vee (not verified) on 10 Jun 2018 - 15:04

      Hi there I think I am around 5-6 weeks pregnant I found out around three weeks ago at the time I was a smoker but quit as soon as I had a positive pregnancy test , I have been trying to eat healthy to lots of fruit and veg when I'm not feeling nauseous but my BMI is 38 which puts me in the obese catagory and i have heard obesity can cause problems in pregnancy and birth I really would like to loose weight in a way that keeps my baby safe .. is there any advice on excersises or other ways to loise weight healthily during my pregnancy please? I am 29 x

    • By Midwife @Tommys on 11 Jun 2018 - 15:30

      Hi Vee, It is very important in your pregnancy that you attend all of your antenatal appointments. Try to eat a healthy balanced diet with at least 5 portions of fruit and vegetables every day and do a minimum of 30 minutes exercise each day. Your maternity team may be able to refer you to a dietician for help in managing your weight. You will also have a glucose tolerance test and advice on cutting down on your sugar intake. Try to cut down on snacks, particularly those high in sugar or carbs and drink water rather than any other drinks which are often high in glucose. Best wishes

    • By Elizabeth (not verified) on 7 Jun 2018 - 06:43

      my LMP was 1st of may and I found out that I am pregnant how many weeks now and when is my due date pls?

    • By Midwife @Tommys on 7 Jun 2018 - 15:06

      Hi Elizabeth, congratulations on your pregnancy.

      If your LMP was 1st May then you are around 5-6 weeks pregnant giving you an estimated due date of 4th February 2019. Hope this helps, take care, Tommy's Midwives x

    • By Anu (not verified) on 5 Jun 2018 - 08:23

      Hi i had my last periods on 12th April and now it's going to be about 8 week. Haven't take any pregnancy test however I am very excited about it. But today feeling stomach cramp and past few days feeling tired and taking naps every now and then. Last year July I had miscarriage after 5 week. Pls advice me what precautions must I take and when must I visit doctor

    • By Midwife @Tommys on 6 Jun 2018 - 12:23

      Hi Anu
      I would recommend that you do a pregnancy test to be 100% sure. If you have a positive test, you can see your GP to confirm the pregnancy, arrange for your antenatal care to start and to book in your first scan for 12 weeks gestation. You will also need to start taking folic acid and pregnancy vitamins if this is the case to help support a healthy pregnancy. If you are not pregnant, i would also recommend that you see your GP to review why your period is late and the symptoms you are having. You may need need to be sent for a gynecology review to put your mind at ease.
      Please take care and i wish you all the best
      Sophie, Tommy's Midwife

    • By Anu (not verified) on 6 Jun 2018 - 14:07

      Hi Sophie
      Thanks for your advice.
      I did visit GP today pregnancy test was negative he also did scan for me but nothing can be seen in there also. So my GP said I am not pregnant he was suggesting medicine for me so that I can get my periods or he say wait for it to come naturally. I want to wait another 2 weeks. My periods have never been so late so when pregnancy result was negative I was very sad. Anyway thanks for your advice. I really appreciate it

    • By Midwife @Tommys on 6 Jun 2018 - 14:30

      Hi Anu
      I am sorry to hear that it was not the result you were hoping for. But i am glad you are under the care of your doctor who will guide you through. All the best
      Sophie,Tommy's Midwife

    • By Merlene (not verified) on 4 Jun 2018 - 09:59

      I had unprotected sex without him releasing inside me on the 14 March, I got my period in March as normal and also in April but I didn't get it in May, to date I still didn't get it (04.06.18). My period is very regular, however, I did have irregular period before falling pregnant in 1995, which was because of fertility drugs. I couldn't fall pregnant thereafter and my periods were again irregular. its has been regular since 2004, I have been on the pill on and off, I did a pregnancy test on the 26 May, it was negative. Is there a chance that I could be pregnant, I am 47 years old

    • By Midwife @Tommys on 5 Jun 2018 - 14:16

      Hi Merlene,

      Thank you for contacting us. I think it would be best for you to contact your GP for a full assessment. Your lack of period may be hormonal due to use of the pill or it may be normal for you due to your history of irregular periods.

    • By Melissa (not verified) on 1 Jun 2018 - 05:02

      Had my last period on the May 8th. Took a test today May 31st. How many weeks do you think I am

    • By Midwife @Tommys on 1 Jun 2018 - 10:04

      Hi Melissa,
      We date a pregnancy according to the first day of your last period, therefore given the date of the 8th of May you would be about 3 weeks and two days pregnant if you have a regular 28 day cycle.
      Best wishes
      Tommy's midwife

    • By Stace (not verified) on 4 Jun 2018 - 13:29

      Hi I am currently 5 days late on my period me and my partner have new trying for 5 years i am very scared to take a test just incase it's not the answer I won't not really any pregnancy symptoms just really bad wind is this a sign of early pregnancy?

    • By Midwife @Tommys on 6 Jun 2018 - 12:28

      Hi Stace
      I would advise that you take a test when your period is 7-10 days late to get the most accurate positive or negative result. If you take a test too early, it can give a false negative result as the pregnancy hormones (hcg) have not yet had time to build up in your system to be shown by the test.
      If the test is negative and your period is still late, then i would recommend that you go to your GP for a review and explain that you have been trying to conceive for 5 years. They may send you for a gynecology review and request some bloods are taken from you to start the ball rolling.
      Bad wind isn't an obvious sign of early pregnancy, it is just too generic to know without doing a test.
      I wish you all the best
      Sophie, Tommy's Midwife

    • By Jazmin (not verified) on 1 Jun 2018 - 04:33

      Hello I'm Jazmin, I have currently missed my period it's already 5 days late should I take a pregnancy test or should I wait longer? My period was supposed to be 5/25/18

    • By Midwife @Tommys on 1 Jun 2018 - 09:57

      Hi Jazmin,
      If you are five days late on your period and have been having intercourse then yes it would be fine to take a pregnancy test now.
      If you are trying to conceive then, if you are not already, we would advise for you to be taking a folic acid supplement.
      Best wishes
      Tommy's midwife

    • By Sahitya (not verified) on 30 May 2018 - 03:05

      My last period was 25th April now 6 days late period,pregnancy test was negative on 4th day in hospital so doctor conducted blood test and thyroid test.Thyroid was normal but prolactin was 39 but i have pregnancy symptoms .please let me know whether i take medication for this

    • By Midwife @Tommys on 1 Jun 2018 - 09:55

      Hi Sahitya,
      If you are not pregnant then I am afraid that we would be unable to advice whether you need medication or not as raised prolactin levels can be due to several things. If you feel that you maybe pregnant, the prolactin levels rise in pregnancy so this would be very normal and there would be no need for medication. You may want to repeat your pregnancy test in a few days if you continue to have symptoms. Otherwise I hope you have a follow up with your doctor.
      Best wishes
      Tommy's midwife

    • By Kyushu Gor (not verified) on 1 Jun 2018 - 13:32

      My last periods were on7th May so How could I know Am I pregnant or not because always 1 week prior my periods come

    • By Midwife @Tommys on 1 Jun 2018 - 16:53

      Hi Kyushu,
      You won't necessarily know unless you are getting very obvious symptoms. A pregnancy test at this stage may not detect a pregnancy as your hormone level may not yet be high enough. I would advise to wait, and if your period does not come when due then to take a pregnancy test. In the meantime if you are trying to conceive then it is important to be taking a folic acid supplement.
      Best wishes
      Tommy's midwife

    • By China (not verified) on 29 May 2018 - 18:14

      I had my last period on 17 April, how many weeks am i?

    • By Midwife @Tommys on 30 May 2018 - 16:08

      Hi China
      Using your last menstrual period date of 17th April, the most pregnant you would be is around 6 weeks.
      When you go for an ultrasound scan, they will measure the baby and give you a more accurate gestation and due date.
      Congratulations. Sophie,Tommy's Midwife

    • By s mummy (not verified) on 29 May 2018 - 16:46

      I done a clear blue on the 26-5-18 and says I'm 3+ weeks. I don't know the last period I had I just need more information. Can you help?

    • By Midwife @Tommys on 30 May 2018 - 16:11

      Hi S Mummy
      Without knowing the date of your last period, it is impossible to date your pregnancy. To do this accurately, you'll need to go for an ultrasound scan. There they will measure the fetus and give you a current gestation and estimated due date. Your GP can arrange this for you at your local hospital.
      All the best
      Sophie,Tommy's Midwife

    • 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?

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