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7 weeks pregnant

7 months pregnant + iodine


Your baby's development at 7 weeks

During week 7, your baby’s arm buds are emerging and flat, paddle-like hands are forming1,2. Iodine supports your baby’s growth at this time3. Discover which foods contain this mineral, and why you may want to ask your doctor about taking a daily iodine supplement.

Hands are emerging

At 7 weeks pregnant, your baby measures anywhere between 42 and 10mm3 long. They are assuming a more baby-like appearance3, with arms buds becoming longer, and flat, paddle-like hands emerging3.

"Your baby’s development at 7 weeks"

At this stage, your baby’s head is growing faster than their body; a reflection of the rapid and intense brain growth that is happening3. Their heart is also developing, and has divided into distinct right and left chambers. At the same time, air passages are starting to form within the lungs – these will eventually grow into a more complex network of bronchi4.

If you were able to see your baby’s face, you’d be able to spot two tiny nostrils. Their mouth is taking shape too, with lips, a tongue and tooth buds appearing2. Meanwhile, their eyes and inner ear structures continue to develop, although it will be some time before these function properly3.

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Are you getting enough iodine?

Iodine, a mineral found in certain foods, helps make the hormones produced by the thyroid gland5. These hormones assist in regulating metabolism and keeping cells healthy6. Iodine has also been shown to contribute to normal cognitive function7, with one important study showing that the cognitive development of children born to mothers who didn’t get enough iodine during pregnancy being poorer than children whose mums had a good intake8. Studies like these are leading experts to believe that iodine may be more important in pregnancy than was previously thought.

”Good sources of iodine include fish and other seafood, and dairy foods like milk and yogurt.”

The recommended daily intake (RNI) of iodine for women between the ages of 19 and 50 is 0.14mg9. Maintaining an adequate intake during pregnancy supports your baby’s normal growth, as well as helping to regulate your thyroid hormones.

An NHS study in 2011 revealed that many teenage girls in the UK aren’t getting enough iodine from their diet10, and these findings are thought to reflect the iodine status of many people in the UK11. If you’re not sure whether you’re getting sufficient levels of iodine, talk to your doctor or midwife about taking an iodine supplement.

Next Steps

Replacing your regular salt with an iodised version is an excellent way to increase your iodine intake. Boost your iodine levels further by including the following foods as part of your well balanced diet12,13.

  • Haddock
  • Cod
  • Prawns and other pregnancy safe seafood (make sure they are cooked)
  • Milk
  • Yogurt
  • Seaweed

View references

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1. European Union. Commission Regulation (EU) No 957/2010 of 22 October 2010 on the authorisation and refusal of authorisation of certain health claims made on foods and referring to the reduction of disease risk and to children’s development and health Text with EEA relevance. OJ L 279 2010;13-7.

2. Deans A. Your New Pregnancy Bible, The experts’ guide to pregnancy and early parenthood. 4th ed. London: Carroll & Brown Publishers Limited, 2013. p. 32.

3. NHS UK. You and your baby at 0-8 weeks pregnant [Online]. 2013. Available at: [Accessed June 2014]

4. Curtis GB, Schuler J. Your pregnancy week by week. 7th ed. Cambridge: Fisher books, 2011. p. 98-9.

5. European Union. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children’s development and health Text with EEA relevance. OJ L 136 2012;1-40.

6. NHS UK. Vitamins and minerals – Iodine [Online]. 2012. Available at: [Accessed June 2014]

7. European Union. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children’s development and health Text with EEA relevance. OJ L 136 2012;1-40.

8. Bath SC et al. Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC). Lancet 2013;382(9889):331-7.

9. Department of Health. Report on Health and Social Subjects 41. Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. London: TSO, 1991.

10. Vanderpump MP et al. Iodine status of UK schoolgirls: a cross-sectional survey. Lancet 2011;377(9782):2007-12.

11. British Thyroid Foundation. BTA research team: UK is now iodine deficient [Online]. 2011. Available at: [Accessed July 2014]

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

13. BDA. Iodine fact sheet [Online]. Available at: [Accessed July 2014]

Last reviewed: 7th July 2016
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