Week 4: Your Baby is the Size of a Poppy Seed
You may have missed your period and might suspect you are pregnant. hCG hormone levels are rising rapidly, which is what pregnancy tests detect. You may start feeling unusually tired and notice your breasts are tender or slightly swollen.
Your baby at week 4
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Size of a Poppy seed
Baby Development
The blastocyst has implanted into the uterine wall and is now called an embryo. The amniotic sac and yolk sac are forming to protect and nourish the baby. Three distinct layers of cells are developing: the ectoderm (skin and nervous system), mesoderm (heart and bones), and endoderm (lungs and digestive system). The placenta is beginning to form and will soon take over hormone production.
Week 4 Highlight: The embryo is now producing hCG, the hormone that gives you that positive pregnancy test result!
Common Symptoms
Tips for Week 4
Take a home pregnancy test - they are accurate from the first day of your missed period.
If positive, book your first antenatal appointment.
Continue folic acid and start a pregnancy multivitamin if recommended.
Avoid alcohol completely from now on.
South Africa Specific Info
Home pregnancy tests are available at Clicks, Dis-Chem, Pick n Pay, and Shoprite pharmacies for R30-R80. If you cannot afford a test, visit your local public clinic for a free pregnancy test. Once confirmed, register for antenatal care - early registration is encouraged in SA's public health system.
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