Third trimester · 33 weeks pregnant
Week 33: a flexible skull
Skull bones stay soft for birth while the rest hardens.
The bones of the skull remain soft and unfused so the head can mould through the birth canal. The immune system is receiving antibodies, and your baby coordinates sucking, swallowing and breathing.
Size and weight
About the size of
a pineapple
Length
43.7 cm
Weight
1.9 kg
Averages from standard growth charts. Measured crown to rump until week 20 and head to heel afterwards.
How your baby is developing
- Skull bones stay soft and separate so the head can pass through the pelvis.
- The baby tells light from dark and may turn towards a bright window.
- Sucking, swallowing and breathing are coordinated for feeding after birth.
- Antibodies from you build up the baby's immune defences.
How you may feel
- Feeling hot and sweaty
- Breathlessness
- Pelvic pressure
- Swelling
- Insomnia
- Numb fingers
- Braxton Hicks
Your metabolism and blood volume are at their peak, which is why you feel so warm. Light layers, cool drinks and lukewarm showers help.
What's next
Tests and appointments
- From 33 weeks a CTG (cardiotocography) recording of your baby's heartbeat is done about every two weeks until birth.
What to do this week
- Stay cool and drink regularly.
- Practise relaxation and breathing with your birth partner.
- Arrange childcare or pet care for when labour starts, and write down who to call.
Call your doctor or maternity hospital if
- Your baby is moving less than usual, or the pattern has changed
- Vaginal bleeding, or your waters break, especially if the fluid is green or brown
- A severe headache, vision changes, pain under the right ribs, or sudden swelling of your face and hands
- Regular painful tightenings before 37 weeks, or severe itching of your palms and soles
If something feels wrong, trust yourself and call 103 or your maternity hospital. You will never be wasting anyone's time.
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