Week 3: Conception Has Occurred!
You likely won't feel any different yet as it is very early. Progesterone levels are rising to support the potential pregnancy. Some women experience light implantation spotting around 6-12 days after conception.
Your baby at week 3
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Size of a Microscopic cell cluster
Baby Development
Sperm meets egg in the fallopian tube, and fertilisation occurs. The single fertilised cell (zygote) begins dividing rapidly as it travels towards the uterus. By the end of this week, it has become a ball of about 100 cells called a blastocyst. The cells are already differentiating into what will become the embryo and the placenta.
Week 3 Highlight: At the moment of fertilisation, your baby's sex, hair colour, eye colour, and many other traits are already determined!
Common Symptoms
Tips for Week 3
Continue taking folic acid daily - it is critical for neural tube development.
Avoid heavy lifting and extreme exercise.
Do not take any new medications without consulting your healthcare provider.
Maintain a positive mindset - implantation takes a few days.
South Africa Specific Info
Most women in South Africa won't know they are pregnant yet this week. Continue your normal routine and take your folic acid. If you are on chronic medication (e.g., ARVs), do not stop - speak to your doctor about pregnancy-safe options.
All Pregnancy Weeks
Frequently Asked Questions
About the Author
Due Date Calculator SA Editorial Team
Our content is reviewed by healthcare professionals familiar with South African maternal health practices. We combine evidence-based medical information with local knowledge to support South African mums throughout their pregnancy journey. Our team includes contributors with backgrounds in midwifery, obstetrics, and maternal health education.
Last reviewed: February 2026