Morning sickness
Why nausea and vomiting happen in pregnancy, when they ease, what helps and when to call a doctor.
3 min read
First trimester
Week 13 of pregnancy
Your baby is the size of a lemon. This is the last week of the first trimester: the vocal cords form and the baby can suck its thumb.
Your baby is the size of a lemon
- Length, head to bottom
- ≈ 7.4 cm
- Weight
- ≈ 23 g
Your baby this week
- The vocal cords form, though the baby will not make a sound until after birth.
- The baby can bring its thumb to its mouth and suck it.
- The body starts to grow faster than the head, so the proportions even out.
Your body this week
- For many women this is when energy and appetite come back.
- You may notice a small bump, especially if this is not your first pregnancy.
- Your sex drive may change, in either direction; both are normal.
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Read more for this stage
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General information written by the mam.al editors. Every pregnancy is different and sizes are averages; it does not replace advice from your doctor or midwife. Sources include the NHS week-by-week guide to pregnancy. NHS. Contains public sector information licensed under the Open Government Licence v3.0.