Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.

Pregnancy and Fetal Development First Trimester (4 Weeks)

Medically reviewed by Min Clinic Staff | Updated: January 2026

Picture of First Trimester (4 Weeks)

Picture of First Trimester (4 Weeks)
First Trimester: The Baby at 4 Weeks
  • Your baby's brain and spinal cord have begun to form.
  • The heart begins to form.
  • Arm and leg buds appear.
  • Your baby is now an embryo and 1/25 of an inch long.

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