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Pregnancy health centre

5 weeks pregnant

WebMD Medical Reference
Medically Reviewed by Dr Rob Hicks


How is your baby growing at 5 weeks?

In week 5 of pregnancy the embryo will be about 2-4mm, and in the next couple of days it will become pear shaped. A groove will be forming in the top layer of cells (the ectoderm), with the cells folding up and around to form the neural tube. This hollow tube is the start of the baby's nervous system and will form into the brain at the "head end" and spinal cord at the "tail end". Cells migrate from the top of the neural tube and change into various different cell types such as neurons or skeletal tissue. Spina bifida can occur if there are defects in this tube.

The embryo's heart will be a basic tube-like structure that starts to form a bulge in the centre of the embryo. Blood vessels will also form within the embryo by the end of this week. Some of these blood vessels will make up part of the umbilical cord.

How are you changing in week 5?

Most women will realise they might be pregnant when there is no sign of their period and it is overdue. You may be feeling the side effects of the hormones preparing your body for pregnancy, such as tingling breasts, morning sickness and moodiness.

What you need to know in week 5

If you think you are pregnant, or have done a pregnancy test and the results are positive, book an appointment with your GP to start getting the best advice for antenatal care. A healthy pregnancy gives you the best chances of having a healthy baby. You should be taking a daily supplement of folic acid and a daily supplement of vitamin D.

You should be avoiding certain foods that may cause diseases that can cause birth defects or miscarriage. These include:

  • Soft unpasteurised cheese such as goat's, feta, Brie, Camembert, and Stilton and other blue cheeses
  • Unpasteurised milk and juices
  • Raw eggs, including foods that contain raw eggs such as mousse
  • Raw or undercooked meats, fish and shellfish
  • Fish that can be high in mercury such as shark, marlin and swordfish

To avoid contracting toxoplasmosis, have someone else clean the cat litter if you have a cat – do not touch cat faeces.

Next: 6 weeks pregnant

Additional pregnancy week by week pages:
7 weeks pregnant 8 weeks pregnant 
9 weeks pregnant
 10 weeks pregnant


Reviewed on January 16, 2017

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