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 Midwife @Tommys on 23 Feb 2018 - 11:07

    Hi Rashidat,
    According to your period dates this would make you about 10 weeks pregnant. If you have not already, do speak with your GP about being referred for maternity care, you should have a booking appointment with your midwife soon and a scan in the next couple of weeks. At this first scan they will give you a definite due date and date your pregnancy accurately. Best wishes, Tommy's midwives x

  • By Aquarius (not verified) on 22 Feb 2018 - 09:09

    Thank you Sophie and team for your relevant and helpful advice here.

    had another ultrasound from another hospital to check for 2nd opinion. The findings were still the same-missed abortion. But the doctor suggested for another 2 weeks (mar 6) for review. Here are my worries:
    Should I be worried for this waiting period? Will it harm me?
    Is it true that nature can take its course, it means it can expel the blood naturally? Will this process be painful?
    What should I do when I bleed at work?
    What are my chances then?
    I am still hoping that there will be positive result then, like growth change of the sac and fetal pole visibility.
    Thank you for your sympathy and advice.

  • By Midwife @Tommys on 22 Feb 2018 - 16:23

    Hi, Thank you for your comment.

    So sorry to hear your news, I can't begin to imagine how you are feeling at this time. Please be reassured that it can be common practice for a Doctor to wait about 2 weeks, this gives the chance for nature, as you say, to take its course and it can do. You may start to bleed and have abdominal pain, this can be uncomfortable but if your bleeding becomes heavy with clots or your pain increases then it is advisable to be seen either in the early pregnancy unit or if it is out of hours, then you can attend A and E.

    It shouldn't be of harm to you waiting, but just be aware of how you are feeling, seek medical advice if you become unwell or have a temperature, this may indicate that you have developed an infection.

    There is nothing to suggest that things wont happen naturally but if it doesn't then the Dr will see you in 2 weeks, they should rescan you to finally confirm that it is a missed miscarriage and then they will talk to you about your option going forward.

    If you do start to bleed at work, try and keep calm and make sure you have sanitary pads on your bag. It may be advisable that you take it easy over the next couple of weeks, give yourself time and be kind to yourself, maybe rest at home during this time.
    I really hope that whatever the outcome, you are ok and if you need support and reassurance then please call the Tommy's Midwives on 0800 0147 800 Monday to Friday 9am-5pm. Take Care, Tommy's Midwives x

  • By Aquarius (not verified) on 23 Feb 2018 - 00:34

    Hi Sophie,

    Thank you so much for your advice. You have been very helpful to me. I was teary-eyed while reading your reply to my concerns. I can feel the sincerity and sympathy from your advice. I will keep you posted on my situation. More power to you!

  • By Aquarius (not verified) on 20 Feb 2018 - 01:59

    Two weeks ago, I had my scan and it was 6 weeks and 1 day, the gestational sac was visible. And today, I had my check up again and scan and nothing changed. The size of the sac is still the same and the fetal pole is not visible. The doctor said that it could be a miscarriage. Maybe that explained of the spotting I had last week. I haven't had any active spotting for 2 days now. The doctor advised me to have a quantitative HCG test and 3d scan to confirm either I had miscarriage or not. I am really anxious about this. If i opt to do the doctors's advice, it means I would fly to the city (2 hour fight) to have it done which make me feel worried that I might have travel issues, like spotting or bleeding in flight. What should I do?

  • By Midwife @Tommys on 21 Feb 2018 - 09:25

    Hi Aquarius
    I am in agreement with your doctor who feels that the HCG and scan is necessary to properly diagnose if this is a viable pregnancy or not. If the sac has not grown and there is no fetal pole visible, then it does, sadly, sound like it might be a miscarriage. Please do not worry about taking a two hour flight, this will not put the pregnancy more at risk. If you feel unwell during the flight though, please do alert the cabin crew to your condition. Please take care of yourself and i wish you all the best
    Sophie,Tommy's Midwife

  • By astrea (not verified) on 18 Feb 2018 - 12:01

    i have been pregnant for 6 weeks today but i feel abdominal pain, i asked my obg about it and she asked me to take a urinalysis and i found out that i have uti 10-15/hpf actually, do you think this is the reason why i have abdominal pain?


  • By Midwife @Tommys on 19 Feb 2018 - 14:58

    Yes this could be the reason for pain. UTI in pregnancy is usually treated with antibiotics. See your doctor again for treatment and take care x

  • By Kate (not verified) on 16 Feb 2018 - 12:38

    Hi I’ve just found out I’m pregnant and got a doctors appointment in a weeks time. I’ve read up on prenatal vitamins but I don’t really like taking something unless told so by my gp. I’m thinking of waiting and doing as I’m told by gp and not a website on the internet will this be ok I eat quite healthily and just need a bit of information before my appointment.
    Many thanks

  • By Midwife @Tommys on 16 Feb 2018 - 13:42

    Hi Kate,
    It is understandable having worries about taking anything in pregnancy. The most important supplement to take is folic acid, and this is in guidance and has been for a long time to take before conception (where possible) and up until at least the end of the first trimester as this has been shown to vastly reduce the risk of some abnormalities in the baby. The other vitamin which is advised is vitamin D and this is also advised for every pregnant woman as stated in this article. With regards to a multivitamin, this is up to you, if you have a healthy balanced diet then this should be enough for your baby and you do not need to take a multivitamin. I hope this helps, best wishes, Tommy's Midwives.

  • By Joan (not verified) on 15 Feb 2018 - 03:22

    Im 13 weeks pregnant, i feel abdominal pain but very light and i tend to feel a slight pain after i ate, is it normal?

  • By Midwife @Tommys on 15 Feb 2018 - 11:59

    Hi Joan, Thank you for your comment.

    It can be common to feel slight abdominal discomfort in pregnancy with all the ligaments stretching as your baby grows. As your baby grows, your organs will move to accommodate your growing baby so this may be the cause of the discomfort after you eat and it may be indigestion that you are suffering from, again this can be common in pregnancy and you can buy over the counter remedies at your local pharmacy to help with this.

    However, any abdominal pain, if you feel that it is very uncomfortable, should be assessed by a midwife or Doctor. If you are worried then you can always call your GP or midwife who will be able to see you and give you reassurance. Hope this helps, Take Care, Tommy's Midwives x

  • By Aquarius (not verified) on 14 Feb 2018 - 21:22

    I am 7weeks pregnant and still working overseas. I plan to fly back to my country (6 hour trip) in May this year. By then, it will have been 5 months. Is it safe for us to fly then?

  • By Midwife @Tommys on 15 Feb 2018 - 11:36

    Hi, Thank you for your comment.

    It is safe to fly in pregnancy as long as you have no underlying medical condition that a doctor would not permit you to fly. Please click on the following link for more information

    Some airlines won't let you fly without a doctors letter so it is best to check with the airline you are flying with. In flight health is something to be reminded about, take regular breaks and walk around, drink plenty of fluids, avoiding tea or coffee and invest in some flight socks as the risk of DVT increases in pregnancy when flying. Hope this helps, Take care, Tommy's Midwives x

  • By Saba (not verified) on 14 Feb 2018 - 06:42

    I m 11 or may be 12 week pregnant this stage m feeling no pain in abdomen..but at starting of pregnancy i felt minor it normal to feel no pain ..

  • By Midwife @Tommys on 14 Feb 2018 - 12:18

    Hi Saba
    It is perfect that you are experiencing no pain at all. Whilst some pain can be normal, it is better to have no pain at all. So you should be reassured by this.
    If you wish to talk any of this through further, you can call on 0800 0147800
    All the best
    Sophie,Tommy's Midwife

  • By Olivia (not verified) on 12 Feb 2018 - 09:50

    Is it likely to get pregnant on your period? also I am getting little bumps on my areola and i'm not sure what to do, should I wait a little longer and see what happens? I have also had a few headaches in the past couple of days/week. Should i tell someone soon as i'm younger then 18?

  • By Midwife @Tommys on 13 Feb 2018 - 15:36

    Hi Olivia
    Thank you for your email.
    Whilst it is uncommon to get pregnant whilst you are menstruating it is possible. If you think you are pregnant, please see your GP as soon as possible.

  • By Stephanie (not verified) on 12 Feb 2018 - 07:35

    Hi i recently found out i am pregnant.. my last day of my period was 28th november 2017 i worked out i should be 10 weeks i am going to register with a midwife today, what date did i get pregnant working out from these dates? Also is sickness and hotflushes and cold shivers normal too?

  • By Midwife @Tommys on 13 Feb 2018 - 15:34

    Hi Stephanie
    Thank you for your message.
    If the first day of your last menstrual period was 28th November 2017, then you are about 11 weeks pregnant today. If your periods are around a 28 day cycle and regular, you would've conceived around the middle of December 2017.
    Hormonal changes due to pregnancy will fluctuate your body temperature - but if you feel unwell, please see your GP.

  • By Dia (not verified) on 12 Feb 2018 - 07:09

    I m 4 week pregnant and when i wake up in the morning i feel like something stretching in my lower abdominal and i already have 3 miscarriages i also have low progesterone i went to the obg but they r rude with me can u tell me what should i do

  • By Midwife @Tommys on 13 Feb 2018 - 15:29

    Hi - Thank you for your message.
    Congratulations on your pregnancy - I'm sorry to hear of your pregnancy losses and hope you are coping well.
    Light stomach pain at the start of pregnancy is usually caused by your expanding womb and hormones. It can sometimes feel like a ‘stitch’. You may also feel light period-like discomfort or cramps at the beginning and end of pregnancy. These are nothing to worry about.
    However, if you are having persistent abdominal/stomach pain or cramping, it should be checked by a doctor or midwife immediately.

  • By Lynn (not verified) on 11 Feb 2018 - 14:24

    Hi I’m about 5 weeks and am going for a vaginal ultrasound. Doc says I appear bigger than I am registering to be by last period but also asked if I had fibroids. Should I be worried?

  • By Dinah (not verified) on 11 Feb 2018 - 08:08

    I miss period and start to have cramps in my womp my last period was 10th of January

  • By Midwife @Tommys on 13 Feb 2018 - 15:25

    Dear Dinah

    If your last period was on the 10th January 2018 and you think you may be pregnant, it is best if you take a pregnancy test as soon as possible. If you are pregnant it is important that you see your GP to arrange antenatal care and get advice.

  • By Lex (not verified) on 10 Feb 2018 - 16:47

    Hi, I'm 12 weeks pregnant. .as of a few weeks ago I started developing low back sacral pain. It feels like I need to drag my foot when I'm walking. Do you have any advice to remedy this? I saw the chiropractor but it didn't help. Thank you

  • By Midwife @Tommys on 13 Feb 2018 - 15:22

    Dear Lex
    Thank you for your message.
    Mild lower back pain in pregnancy is not uncommon - however, if you are finding it is affecting your mobility then you should contact your GP urgently for advice and support.

  • By Grace (not verified) on 9 Feb 2018 - 21:39

    Hello, I got pregnant for the first time (1st try) in May 2016 when I was 38 years old, but unfortunately I had a miscarriage when I was 6 weeks pregnant. Last Tuesday the 6th February I did a pregnancy test and I was 1/2 weeks pregnant but I did the test later in the morning after having two cups of teas. When I went to the nurse yesterday to confirm the pregnancy, and after she checked with her calendar. she confirmed that I am 4 weeks pregnant Andy not 1/2 weeks. She said this was due to the test that I had at home on a later morning didn't show the exact weeks.
    I been having a lot of bad back and sometimes abdominal pain (similar to a period cramps or trapped wind rather than pain). Is this normal? Or it's a sign of miscarriage. I'm quite worried as I keep thinking that I'm going to have another miscarriage. Please can you advice? Many thanks.

  • By Midwife @Tommys on 13 Feb 2018 - 15:20

    Dear Grace
    Thank you for your message.
    Some abdominal pain and mild cramps are common in early pregnancy, however they should all be checked by a midwife or doctor - please contact your midwife/doctor to arrange an appointment to be checked.

  • By Kaija (not verified) on 9 Feb 2018 - 08:25

    I just found out I'm pregnant I had my last cycle at the end of December 30 begin Jan I just found out I'm pregnant three days ago how far along am I and I'm wounder around what date I got pregnant can someone help me

  • By Midwife @Tommys on 9 Feb 2018 - 15:54

    Hi Kaija,
    According to the dates that you have provided, based on you having a regular 28 day cycle, if the first day of your last period was 30 December then it would make you about 5 weeks and 6 days pregnant. It would be likely that conception occurred the days around the 14th of January. I hope that makes sense, if you would like to talk further then please do email us [email protected] Best wishes, Tommy's midwives.

  • By Gemma (not verified) on 7 Feb 2018 - 22:01

    Hi I’ve just found out I’m pregnant I haven’t had a period since the 5th Dec... I had a blood test and my hcg levels are 72’000 I’ve also had a scan which shows it’s twins and heartbeats were detected but my gynaecologist says I’m only 4-5 weeks pregnant is this possible?

  • By Nani (not verified) on 7 Feb 2018 - 04:27

    Hello I had my last period on around December 21st and took 4 home pregnancy test the 1st 3 i took on January 25th and were positive but not that clean. The last one was on February 1st and was more clear but the week after my missed period i felt like this fullness as if I were about to have a heavy period but nothing along with cramping and after intercourse i start brown spotting throughout the day and still have some cramping throughout the day is this normal?

  • By Midwife @Tommys on 7 Feb 2018 - 11:25

    Hi Nani
    It sounds like you may be best to go to your GP to have one more pregnancy test done there to be 100% sure.
    If you have cramping and spotting and are pregnant, then the GP should refer you to your local early pregnancy assessment unit for review there. If you are not pregnant, then you may be considered to be sent for Gyane testing if the GP is concerned by your symptoms and medical history. Please take care of yourself
    Sophie,Tommy's Midwife

  • By Hat (not verified) on 5 Feb 2018 - 16:35

    So I’ve been having unprotected sex with my partner for 3 months now my last period was the 8th jan I was supposed to be due on today which is the 5th Feb and this morning as I wiped it was pink blood then nothing else I’ve been feeling a little dizzy an sick lately on an evening does this sound like I’m pregnant ?

  • By Midwife @Tommys on 7 Feb 2018 - 11:22

    Hi Hat
    It would be sensible for you to do a pregnancy test to be sure. It sounds as if you and your partner are trying to conceive, so this does sound possible.
    The pink loss could also simply be the start of your period. So both options are possible.
    Feel free to get back in touch if you need more support or advice.
    Sophie,Tommy's Midwife

  • By Sheila Davis (not verified) on 5 Feb 2018 - 12:22

    Please help the start of my last monthly was November 16, 2017. I should have started my next monthly on December 26, 2017. That day all I did was streak. In January my monthly still hasn't showed up. I have taken to home pregnancy test both came back negative. I also have had a blood test done also negative. I have all of the signs of being pregnant. Could I be pregnant and it not show up on either test.

  • By Midwife @Tommys on 7 Feb 2018 - 11:19

    Hi Sheila
    It would be best to go to your GP to discuss this further. If you are 100% not pregnant, then the GP needs to refer you on for a Gynaecology review at your local hospital as you could have some type of hormonal imbalance that needs addressing. Please do not worry about this at this stage, changes can occur in menstruation patterns, but these are always worth getting check out to put your mind at ease! Please feel free to call us if you need to talk things through
    Sophie,Tommy's Midwife

  • By bebe (not verified) on 31 Jan 2018 - 10:12

    i last had sex on 6 January this year. and my last period was somewhere on the 16/17th DEC but haven't had any since ,got tested twice it came back negative but been having cramps and back aches,feel bit dizzy at i exaggerating?

  • By Midwife @Tommys on 31 Jan 2018 - 11:50

    Hi Bebe. The most pregnant you could be is only 3- 4 weeks maximum.
    It might be best to go to your GP to get another test to be 100% sure. And also if you are not pregnant, you may need a referral to a gynecology specialist if these episodes are happening due to your menstrual cycle/changing hormones.
    Take good care of yourself
    Sophie, Tommy's Midwife

  • By Leann (not verified) on 31 Jan 2018 - 02:40

    Hi, I just found out 3 days ago I’m pregnant and I have type 2 diabetes my sugars are usually 250/300 I eat well and exercise but I can’t keep them down. I was told I’m high risk due to being diabetic, I’m going to see a specialist but I’m very concerned about my baby what could happen to the baby??

  • By Midwife @Tommys on 31 Jan 2018 - 11:46

    Hi Leann. Congratulations on your pregnancy. Please don't panic about your diabetes - pregnancy is a time of change that does need to be managed, but many pregnant women with diabetes have a happy and healthy 9 months.
    Please go to your GP asap since you know that you are pregnant to discuss referral to a specialist team in pregnancy (due to your diabetes) and to be booked in for your first scan.
    Please feel free to call us if you wish to discuss anything further
    Sophie, Tommy's Midwife

  • By LeAnn (not verified) on 1 Feb 2018 - 21:58

    I have an appointment on Monday to see the specialist. I pray all goes well! Thank you for your help!

  • By Aquarius (not verified) on 30 Jan 2018 - 18:57

    I had my period last December 26.I always have regular period. Now, it's delayed for 4-5 days. I was bothered because I had loose bowel movement for 4 days, my breasts were tender and sensitive, I had migraine (which normall happens a day before my period). So i thought, i would have red day then but it didnt. ldid PT a couple of days ago, midday, and it was positive.I took a second one, and it was blurry. Today, i did the test again, anf it was blurry. Pls advise whether i am pregnant or not. I am feeling the signs for my period, but it's not happening. Thank you.

  • By Midwife @Tommys on 31 Jan 2018 - 11:41

    Hi Aquarius.
    It is difficult to say. I would suggest that you go to your GP surgery to have a test done there. If you have had unprotected sex, then it may be possible. But it would make sense to go to your GP to be 100% sure either way so that a scan can be arranged if it is positive to date the pregnancy. Please feel free to call us if you wish to discuss this further.
    Sophie,Tommy's Midwife

  • By Aquarius (not verified) on 6 Feb 2018 - 19:59

    Thank you for your advice. It's confirmed that I am pregnant at 37.I am bearing my 2nd child.
    Please enlighten me if it is safe to workout during the first trimester? What are the do's and dont's? I have been hitting the gym for a year now. Await for your advice. Thanks.

  • By Midwife @Tommys on 7 Feb 2018 - 12:03

    Hi Aquarius
    It sounds as if you are a fit woman, and there is no need to stop exercising suddenly now that you have found out that you are pregnant unless you are at very high risk during your pregnancies. It might be a good idea to inform your gym instructor that you are pregnant so that they can tailor your class/exercise to you during pregnancy. Staying fit and well has many benefits for both you and baby - so keep up the awesome work mummy!
    Sophie, Tommy's Midwife

  • By Marie (not verified) on 30 Jan 2018 - 17:45

    Hi question I'm going to be a first-time mom and I want to know is it normal not to have any symptoms at all or have your LPM since November and if you have morning sickness one day and then the other day is gone is that normal or have you had a miscarriage but you do not bleed or anything just have morning sickness that one time and then it's gone but no symptoms at all the whole 2 months which Jan 27 made (2) months so I did blood work and test and it said that you're pregnant but don't feel any symptoms at all. Stomach felt tight and full one minute and feel normal the next had a few pelivc pain and light cramps nothing steady.. no period Since November 27th so is it normal to feel that way and not have any symptoms at all no nausea no vomiting just stomach and bathroom bowel movements? should I be worried about anything I'm praying all is fine and that no missed Carry or that the baby had stopped growing... Trying to stay calm and don't stress.. please help

  • By Midwife @Tommys on 31 Jan 2018 - 11:38

    Hi there Marie
    Many women experience no pregnancy symptoms at all. Whilst i can appreciate that this feels stressful, some would say that you are lucky as many pregnancy symptoms can make a woman feel quite unwell, especially in that first trimester. An absence of symptoms, does not make the pregnancy unhealthy or pose a risk to fetal development.
    If you wish to call and have a chat about this further, please feel free to call us on 0800 0147800
    All the best
    Sophie, Tommy's Midwife

  • By Princella (not verified) on 30 Jan 2018 - 09:14

    Ive had unprotected sex last two months(december) .My menses didnt show up this January and ive been excited that im already pregnant;only to wake up this morning to see my menses.When can i use a test stip ? Could it be that i wasn't pregnant ? Im confused. Please help

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