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.


Follow Tommy's PregnancyHub on Instagram

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 Maryam (not verified) on 13 Mar 2018 - 21:15

      I had my last period on 19th of January.pls hw old is my pregnancy nw.

    • By Midwife @Tommys on 15 Mar 2018 - 15:55

      Hi, given the date of your last period and assuming that you have regular 28 days cycle, then you are about 7 weeks and 6 days pregnant, due about the 26th October. When you have your first scan then you will be given an official due date and this will be used for the rest of your pregnancy. If you have not already then we would advised for you to make an appointment with your GP and start taking a folic acid supplement. Best wishes, Tommy's midwives.

    • By feba (not verified) on 12 Mar 2018 - 19:30

      Hello, my LMP was 12th January 2018. I used the pregnancy test and its positive for having a two lines. Then i feel pregnant. After two days i consult a gynacologist.He said everything is ok. He gave vitamin tablets only. He also said March 23 -first scan.Is it correct? How old (how many weeks are my now?is my baby now? In these days i desire and thurst for sexual relationship.Is it wrong or have side effects? When would be my due date?

    • By Midwife @Tommys on 13 Mar 2018 - 12:17

      Hi Feba,

      If your LMP was 12/1/18 then your first scan on March 23rd would be at 10 weeks. Your due date would be October 19th although this is only a guess date as your baby will arrive any time between 37-42 weeks.
      At the moment you are 8 weeks and 4 days. It is fine to have sex in early pregnancy providing that you haven't had any bleeding and it feels comfortable for you. You might need to experiment with positions.

      Have a good pregnancy and get in touch if you have any more questions
      Anna- Tommy's Midwife

    • By Aquarius (not verified) on 9 Mar 2018 - 21:17

      Hi Sophie.
      I just had my D & C procedure done on March 5, 2018 due to unviable pregnancy. And lately, I have been feeling some abdominal discomfort. Is this normal? I am still on medication (antibiotics) for 7 days. I am also on my sick leave. The doctor failed to inform me of what to expect after the procedure. My concers are:
      1. When will my regular menstruation come back?
      2. How soon can I recover?
      3.When can I start going to the gym?
      4.When will it be safe for sex?
      5.other info pls

      Thanking you in advance for the advice.

    • By Midwife @Tommys on 12 Mar 2018 - 10:22

      Hi, I hope you are feeling better today and that your discomfort is resolving. Recovery time varies but you should feel better and stronger each day. If you don't or if you are concerned please see your GP for advice.
      NHS have very good website to answer all your queries or you are welcome to call us on 0800 0147 800 if you need to talk. We are here Monday to Friday 9-5pm.

    • By Ash (not verified) on 9 Mar 2018 - 15:28

      Hello, iam 4 wk pregnant but i had an abdominal pain sometimes specially i feel pressure and mostly my pain started after pee , like periods pain .i am taking snooty is it safe

    • By Midwife @Tommys on 9 Mar 2018 - 16:14

      No I would not advise any medication in pregnancy without discussion with your doctor. Make an appointment as soon as you are able. Best wishes

    • By Crystal (not verified) on 9 Mar 2018 - 09:44


      The first day of my last period was 2nd of January 2018. My period cycle is 40 days on an average. When would be my due date?

    • By Midwife @Tommys on 9 Mar 2018 - 11:12

      If we go by your LMP (last period) your due date would be 11th October. However this date may be reviewed at your first scan as you have a long cycle length.

    • By maryann (not verified) on 7 Mar 2018 - 09:51

      My last period is 29th January,2018 and iam many weeks are my now?

    • By Midwife @Tommys on 7 Mar 2018 - 09:58

      Hi Maryann
      The most pregnant you could be is around 5 weeks using your last menstrual period date of 29th Jan 2018.
      The weeks may change slightly when you go for your first pregnancy scan.
      All the best
      Sophie, Tommy's Midwife

    • By tina (not verified) on 5 Mar 2018 - 14:33

      am 6 weeks pregnant, I have stomach ache recently and my doctor prescribed buscopan for me. is it safe to take

    • By Midwife @Tommys on 6 Mar 2018 - 14:36

      Hi Tina,
      Thank you for your post. You are concerned about taking buscopan whilst pregnant. There is no medical research that says that Buscopan is dangerous for the developing baby. For many drugs there is inadequate evidence available to establish whether the drug is 100% safe and it would be unethical to test drugs on pregnant women so we tend to err on the side of caution in pregnancy . It is in the first 12 weeks that the baby's major organs are developing. How bad are your symptoms? As the effects of the drug are not fully known could you try alternative non medical treatment for your stomach ache until after 12 weeks?
      The link below is for Medicines in pregnancy (BUMPS)
      they are a great resource into what you can and may not want to take. Your local pharmacist can also be a great person for information on drugs in pregnancy and whilst breastfeeding.
      I hope this helps Tina.
      Wishing you a great pregnancy
      Anna-Tommy's Midwives

    • By Mika Lane (not verified) on 5 Mar 2018 - 06:41

      Good day! my last menstruation is last January 10 2018 although my expectation is Jan. 07 2018 and my mentruation lasts for 7 days and more... For the month of Feb. I am expecting that my menstruation will starts at around Feb 13 2018 considering my 3 days delay routine of menstruation. But until now my menstruation is delayed. I used the pregnancy test and its positive for having a two lines. Now I feel pregnant, yes but how old is baby now.

    • By Midwife @Tommys on 6 Mar 2018 - 12:47

      Hi Mika!
      If your last period was in January and the first day of your last period was the 7th you are now around 8 weeks pregnant. It would be good to see your GP and get an appointment to meet your midwife. In the meantime it is important to take folic acid and vitamin d or a pregnancy vitamin that may include these nutrients. If you have any other questions you can email us at [email protected] or follow this link.
      Warmest wishes
      Anna-Tommy's Midwife

    • By Scragfinch (not verified) on 2 Mar 2018 - 11:15

      Hello. I had a stillbirth 5 months ago at 34 weeks due to a silent placental abruption. I have just found out I'm pregnant again and am pleased but very nervous. I want to get a referal to a top obsteatrician I have heard of. What is the best way of doing this? Can my GP do it? I have lost confidence in the midwife checks and think I need a lot more care this time. Many thanks.

    • By Midwife @Tommys on 2 Mar 2018 - 13:10

      I am so sorry to hear about the loss of your baby and it is completely understandable that you are feeling very nervous upon finding out that you are pregnant again. For this pregnancy you will be referral to a consultant at the hospital you choose to book at, you do have the option to request a particular consultant if you would like to, just tell your midwife at your booking appointment. You will have extra appointments, tests and scans in this pregnancy as part of guidelines. We do also have a research centre based in Manchester called the Rainbow clinic who specialise in caring for pregnant women who have had a stillbirth previously, if you would like more information about this then please do email us [email protected] Best wishes, Tommy's midwives x

    • By Sonia (not verified) on 28 Feb 2018 - 05:32

      Hi Tommy,

      When I was 6 weeks pregnant, I got a slight bleeding and we checked with the doctor. On scanning the baby was fine. I have dark brown/light coffee color discharge in the morning when I wake up and check. Doctor says it's not acceptable to get color change like this and and given me some medicine. But it continues every morning and disappears after 10 am usually. Then I could see white discharge only. I am totally worried since this is my first pregnancy. Now I am on 7th week (I had my last periods on Jan 9th). Please advise.


    • By Midwife @Tommys on 28 Feb 2018 - 12:31

      Hi Sonia
      It sounds as if you may have a thrush infection (the white discharge) which should be treated with thrush cream suitable for pregnancy. Antibiotics can also commonly cause thrush, if this was the medication the dr gave to you- i presume you have an infection of some sort. Please continue to take the medication the dr prescribed, but i do recommend that you go back to be reviewed again in view of the discharge/vaginal loss.
      Please take good care of yourself,
      Sophie,Tommy's Midwife

    • By Sohana (not verified) on 26 Feb 2018 - 13:53

      Hi dear,
      I had my last period on 27 december 2017. I was supposed to have my next mens on 27th january but I missed. I did a test and it's positive. As usual, my pregnancy duration will be almost 8 weeks since last period. But I know it's not coz we had sex with protection except only once that's on 20 January 2018, 7 days before my last period. So what week am I in?

      Also people advising me to see OB for prenatal vitamins. Is it necessary now or I can just intake folic acid and Vitamin D tablets from pharmacy stores?

      People advising me to stop drinking tea but if I stop, I will have constipation. Coz tea is my daily routine to avoid constipation. Should I stop even if I have constipation or I can carry on just the tea. I stopped coffee.

      Thanks for your advice!

    • By Rashidat (not verified) on 22 Feb 2018 - 09:48

      I had my last period 14th December, 2017, did a urine p.t,and positive since January 11th. I have been having series of nausea and vomiting, chills at night,and light abdominal cramps.

    • 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.

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