Your baby this week
Your baby is far too tiny to see yet, but already settling in. Right now your baby is a little cluster of cells about the size of a poppy seed, burrowing into the lining of your uterus so you can grow together. The cells are splitting into two parts — one half will become your baby, and the other half will become the placenta, your baby's lifeline to you. The amniotic sac and yolk sac are forming too. It's the very beginning of everything.
Your body this week
You may have just seen that faint second line — take a breath. This week your baby is implanting snugly into the lining of your uterus, and your body is quietly beginning one of the most remarkable transformations it will ever go through. You might feel mild cramping, light spotting (called implantation bleeding), or simply nothing at all — both are completely normal. Tender breasts, a wave of tiredness, or an unusual metallic taste can start showing up. It's very early, so be gentle with yourself: rest when you can, start your folic acid if you haven't already, and try not to worry about every twinge. You are doing everything right just by being here.
Common symptoms this week
Every pregnancy is different — you may notice some of these, all of them, or none at all. None of this is a checklist to worry over.
- Mild cramping or light spotting
- Tender, sensitive breasts
- Waves of early tiredness
- A strange metallic taste
- Or no symptoms at all
This week’s checklist
- Start (or continue) folic acid 400–800 mcg daily — it protects my developing spine and brain
- Stop smoking, alcohol, and recreational drugs completely
- Check every current medication with your doctor before the next dose
- Avoid raw/undercooked meat, unpasteurised dairy, and high-mercury fish
- Note the date of your last period (LMP) — you'll be asked at every appointment
- Book your first prenatal appointment for around Week 7–8
What’s normal this week
Most of what you’re feeling is your body doing exactly what it should — the everyday symptoms don’t need a call. The signs below are the rare exceptions: noticing one doesn’t mean something’s wrong, just that it’s worth a quick check.
When to call your doctor
- Heavy bleeding (soaking a pad in under an hour) or bleeding with clots
- Severe one-sided abdominal or shoulder-tip pain — can be a sign of ectopic pregnancy
- Fainting, dizziness, or a racing heart along with spotting
- Fever above 38°C (100.4°F)
This guide offers general information for a typical pregnancy and is not a substitute for personalised medical advice. Always follow your doctor or midwife’s guidance for your situation.
Frequently asked questions
How big is my baby at 4 weeks pregnant?
At 4 weeks pregnant, your baby is about the size of a poppy seed.
What are common symptoms at 4 weeks pregnant?
Common symptoms around 4 weeks pregnant include mild cramping or light spotting; tender, sensitive breasts; waves of early tiredness; a strange metallic taste; or no symptoms at all. Every pregnancy is different — you may notice some of these, all of them, or none at all.
What is developing at 4 weeks pregnant?
Your baby is far too tiny to see yet, but already settling in. Right now your baby is a little cluster of cells about the size of a poppy seed, burrowing into the lining of your uterus so you can grow together.
When should I call my doctor at 4 weeks pregnant?
Call your doctor at 4 weeks if you notice heavy bleeding (soaking a pad in under an hour) or bleeding with clots; severe one-sided abdominal or shoulder-tip pain — can be a sign of ectopic pregnancy; fainting, dizziness, or a racing heart along with spotting; fever above 38°C (100.4°F).
Last updated June 2026
References
Ovyacare’s guidance is written in-house and aligned with leading medical authorities: