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Pregnancy Guide·Second Trimester

Week 23: Rapid Brain Development

Large mango (~20cm crown-rump)·Last reviewed: 25 April 2026
Quick answer

At week 23, your baby's brain is developing at an extraordinary pace. The baby weighs about 500g and is becoming more responsive to sound and touch. According to Nuhah's pregnancy guide, this is a period of rapid neurological growth.

Baby development at week 23

Brain development is accelerating. The baby weighs about 500g and is roughly 29cm from head to toe. They are becoming more responsive to sound and touch. Blood vessels in the lungs are developing in preparation for breathing. The baby has a regular pattern of sleeping and waking. Skin is still wrinkled as the body has not yet filled out with fat.

Your body this week

Your bump is growing and you may notice stretch marks developing. Swelling in the ankles and feet can increase. You may feel Braxton Hicks contractions for the first time. Appetite is generally strong. Some people experience restless legs, especially at night.

Things to do this week

1
Pay attention to your baby's movement patterns
2
Start thinking about birth preferences
3
Continue gentle exercise and hydration

Frequently asked questions

What happens at 23 weeks pregnant?

Your baby is going through rapid brain development, weighs about 500g, and is increasingly responsive to sound and touch. You may start feeling Braxton Hicks contractions and notice increased ankle swelling.

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