Week by week / First trimester
Week 5
Your baby is about the size of a sesame seed. Here is what is happening, what you might feel, and the two or three things worth doing this week.
Size right now
A sesame seed
0.3 cm / 0.1 in
- Length
- 0.3 cm / 0.1 in
- Trimester
- First
- To go
- 35 weeks
The baby
The neural tube, which becomes the brain and spinal cord, is forming and closing. The heart is a tube that starts to beat this week.
You
Missed period. Sore breasts, tiredness that feels like flu, and for some people nausea already. hCG is doubling roughly every two days.
This week
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Averages, not targets. Babies vary a great deal and a scan that reads differently from this page is not a problem. Anything that worries you is a call to your midwife or doctor, not a search.