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12 weeks pregnant

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Your baby's development at 12 weeks

In your 12th week of pregnancy, your uterus grows over the top of your pubic bone and you may notice the first signs of a bump. At 12 weeks, your baby’s brain is continuing its development too. Long chain polyunsaturated fats (LCPs), especially docosahexaenoic acid (DHA), are an essential ingredient for healthy grey matter. Learn what to eat to provide your baby with the beneficial fats they need.

Are you showing?

At 12 weeks pregnant, your baby is around 6cm in length, having doubled in size in the last 3 weeks alone1. 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.

"Your baby’s development at 12 weeks"

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

Omegas 3 and 6: Fats with benefits

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 development5. 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.

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A daily serving of healthy fats

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.

Next Steps

Try these Omega 3-rich snacks and small meals6:

  • 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

View references

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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. 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.

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

Last reviewed: 7th July 2016
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