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First trimester · Doctor-reviewed

Pregnancy Week 4: What to Expect

✍️ Baby Circle Medical Team🗓️ Updated Jul 2026
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Medically reviewed by
Baby Circle Medical Board
Reviewed on 12 July 2026
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Your baby is about the size of a Poppy seedApprox. ~2 mm · First trimester

Your baby this week

Your baby is a tiny ball of fast-dividing cells (a blastocyst) burrowing into the womb lining. The amniotic sac and placenta start forming, and the neural tube — the future brain and spinal cord — begins to develop.

Your body this week

A missed period and a positive test are the usual first clues. You may notice light implantation spotting, mild cramps, tender breasts and tiredness as hCG rises.

💡 Tips for week 4

  • Start folic acid (400–800 mcg) today if you haven't
  • Stop alcohol and smoking completely
  • Note the first day of your last period for dating

✅ To do this week

  • Confirm with a home pregnancy test
  • Book your first antenatal appointment
  • Review any medicines with your doctor

Common questions — Week 4

Is spotting at 4 weeks normal?

Light implantation spotting can be normal, but heavy bleeding or severe pain needs prompt medical attention.

Why folic acid so early?

It helps prevent neural-tube defects, and the neural tube is forming right now — so earlier is better.

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References

  1. World Health Organization (WHO). WHO recommendations on antenatal care for a positive pregnancy experience. who.int
  2. American College of Obstetricians and Gynecologists (ACOG). Your Pregnancy and Childbirth. acog.org
  3. NHS. Week-by-week guide to pregnancy. nhs.uk
  4. Centers for Disease Control and Prevention (CDC). During Pregnancy. cdc.gov
  5. UNICEF. Maternal and newborn health. unicef.org
  6. Indian Academy of Pediatrics (IAP). iapindia.org
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Medical disclaimer: This article is for general education only and is not a substitute for professional medical advice. Always consult your doctor about your pregnancy, and seek care immediately for any warning signs. Reviewed by the Baby Circle Medical Board.