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      12 weeks pregnant: Pregnancy Symptoms & Baby Development

      Fish During Pregnancy

      12 weeks pregnant: Pregnancy Symptoms & Baby Development

      Read time: 4 minutes


      12 weeks pregnant: Pregnancy Symptoms & Baby Development


      Month 3 (Trimester 1)


      Baby development at 12 weeks

      Your baby’s brain is continuing to develop.


      First scan

      If you haven’t already, it’s time to book an appointment for your 12 week scan.


      Omegas 3 and 6

      Discover how these beneficial fats support the development of your baby’s brain.

      Baby development at 12 weeks

      Foetus Pregnancy Week 12


      What does my baby look like? And, what size is my baby?

      At 12 weeks pregnant, your baby is around 6cm in length, having doubled in size in the last 3 weeks alone1, and is roughly the size of a plum. Amazingly, your baby is now fully formed, with vital organs, bones and muscles in place, all ready to grow and mature over the coming months2.

      Your baby’s head is still large compared to their body, but they now have very definite facial features and their eyelids are now visible, although they will remain closed for some time3. In their mouth, 20 small buds sit inside the gums, which will eventually emerge as baby teeth4.    


      Expert advice

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      Pregnancy at 12 weeks (first trimester)

      First scan

      You are likely to have your first ultrasound scan when you’re around 12 weeks pregnant. 

      Pregnancy Scan

      Also known as the dating scan, it allows your midwife to get a more accurate idea of your baby’s due date. It’s often at this time that mums choose to share their news with family, friends and colleagues.


      What’s happening in my body?

      At 12 weeks pregnant, you could see the beginnings of a baby bump, although this isn’t true for everyone.

      Early pregnancy symptoms at 12 weeks5

      Early pregnancy symptoms vary from person to person. At 12 weeks, you may experience any of the following signs of pregnancy, or no symptoms at all:


      Early pregnancy symptoms vary from person to person. At 12 weeks, you may experience any of the following signs of pregnancy, or no symptoms at all:

      Your breasts may become larger and feel sore. You may also find your nipples stick out more than usual and darken in colour as your body begins to prepare for breastfeeding. 

      During the first 12 weeks, hormonal changes can leave you feeling tired or exhausted. 

      Morning sickness affects up to 80% of mums-to-be in the first trimester6. It can strike at any time of the day or night and varies from mild nausea to sickness throughout the day.

      The pregnancy hormone progesterone slows down your digestion which can lead to bloating and excess gas7.

      Light cramping and spotting are common in the early stages of pregnancy8,9. If the pain becomes severe (stronger than period cramps) or if bleeding becomes heavy, you should talk to your GP.

      Frequent trips to the bathroom are one of the most common symptoms of early pregnancy, as your growing uterus begins to put pressure on your bladder.

      Pregnancy hormones, oestrogen and progesterone, soar during the first 12 weeks of pregnancy10, affecting how you’re feeling emotionally. Get plenty of rest and light exercise to keep you feeling like yourself.

      Focus on Omegas 3 and 6

      The fatty acids Omega 3 and 6 support the healthy development of your baby’s brain, and can only be obtained from your diet11. Making sure you include good sources of Omega 3 in your diet will help you give your baby the best start for a healthy future.

      Making sure you include good sources of Omega 3 in your diet will help you give your baby the best start for a healthy future.

      Cereal With Milk

      Try these Omega 3-rich snacks and small meals12:

      • Mackerel on a slice of wholegrain toast
      • Grilled salmon with steamed leafy vegetables
      • Salmon fishcakes
      • A handful of nuts and seeds
      • A bowl of wholegrain cereal


      OMEGAS 3 & 6

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      Omegas 3 and 6 are two types of long chain polyunsaturated fatty acids, collectively called LCPs. One of the Omega 3 LCPs, known as docosahexaenoic acid, or DHA for short, contributes to your baby’s brain development13. It also supports the normal development of your baby’s eyes and is associated with development post-birth, specifically normal visual development throughout the first year.

      To support your baby’s brain development, try to include an extra 200mg of DHA each day. Oily fish are an excellent source and eating 1-2 portions of oily fish per week will provide sufficient DHA for you and your baby. However, it’s recommended that you eat no more than two portions per week due to the toxins they may contain. For a healthy intake of other Omega 3 fats on the days you don’t eat oily fish, snack on a handful of nuts or start your day with a bowl of wholegrain cereal.


      How much weight should I gain during pregnancy?

      Weight gain during pregnancy depends on your pre-pregnancy weight, and varies a great deal from mother to mother. Most women gain between 10kg and 12.5kg (22–28lb) while pregnant, some of which is the weight of the growing baby14. Learn everything you need to know about weight gain in pregnancy.


      If you haven’t been to see your GP yet, you should make an appointment so they can start planning your antenatal care, including your first ultrasound scan.

      1. Murkoff H, Mazel S. What to Expect When You’re Expecting. 4th ed. London: Simon & Schuster Ltd, 2009. p. 169.

      2. NHS UK. You and your baby at 9-12 weeks pregnant [Online]. 2013. Available at: [Accessed June 2014]

      3. Stoppard, M. New Pregnancy and birth book. The classic Guide for parents to be. New York: Ballantine Books, 2009. p. 83.

      4. Medline Plus. Fetal development [Online]. Available at: [Accessed June 2014]

      5. NHS. Signs and symptoms of pregnancy [Online]. Available at: Page last reviewed: 6 October 2018. Next review due: 6 October 2021.

      6. Noel M. Lee, M.D., Gastroenterology Fellow and Sumona Saha, M.D., Assistant Professor of Medicine. Nausea and Vomiting of Pregnancy. 2011. Pub 2013. [Online] Available at:

      7. NHS Start 4 Life. 1st trimester, week 10 [Online]. Available at:

      8. NHS. Vaginal bleeding in pregnancy [Online]. Available at: Page last reviewed: 26 January 2018. Next review due: 26 January 2021.

      9. NHS. Stomach pain in pregnancy [Online]. Available at: Page last reviewed: 1 May 2018. Next review due: 1 May 2021.

      10. Claudio N. Soares and Brook Zitek. Reproductive hormone sensitivity and risk for depression across the female life cycle: A continuum of vulnerability? 2008. [Online] Available at:

      11. British Nutrition Foundation. N-3 fatty acids and health [Online]. 2000. Available at:

      12. Gandy J (ed). Manual of Dietetic Practice. 5th ed. Oxford: Wiley Blackwell, 2014. p. 759.

      13. European Union. Commission Regulation (EU) No 440/2011 of 6 May 2011 on the authorisation and refusal of authorisation of certain health claims made on foods and referring to children’s development and health. OJ L 119 2011;4-9.

      14. NHS choices. How much weight will I put on during my pregnancy? [Online]. Available at: Page last reviewed: 18 October 2018. Next review due: 18 October 2021.

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      Your baby's future health begins here

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      Questions about feeding and nutrition?

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