4 Weeks Pregnant
At 4 weeks pregnant, your baby is about the size of a poppy seed.
- Length
- 2 mm
- Weight
- less than 1 g
- Trimester
- First
- Month
- Month 1
- Weeks to go
- 36
Size of a poppy seed
Your baby at 4 weeks
Your baby is now an embryo about the size of a poppy seed, nestled into your uterine lining. The cells are sorting into layers that will become every organ, and the placenta and amniotic sac are starting to form.
Your body at 4 weeks
Your period is due this week. The embryo is releasing hCG, the hormone a pregnancy test detects, so a positive test is possible from around the day of your missed period.
Common symptoms at 4 weeks pregnant
- Missed period
- Sore or swollen breasts
- Fatigue
- Light cramping
Every pregnancy is different. Having none of these symptoms is normal too.
Tips for week 4
- Take a home pregnancy test with your first morning urine.
- Call your doctor or midwife to book your first prenatal appointment.
- Use a due date calculator to work out how far along you are.
Your week 4 checklist
- Take a home pregnancy test
- Book your first prenatal visit
- Work out your due date
Helpful at 4 weeks
4 Weeks Pregnant: your questions answered
How big is a baby at 4 weeks pregnant?
At 4 weeks your baby is about the size of a poppy seed: around 2 mm long and weighing less than 1 g. Every baby grows at their own pace.
How many months is 4 weeks pregnant?
4 weeks pregnant is month 1 of your pregnancy, in the first trimester. Your due date is 36 weeks away.
What are the symptoms at 4 weeks pregnant?
A missed period is the main sign. You may also have sore breasts, tiredness, light cramping or spotting. Many people have no symptoms yet.
Sources
This guide is written from public guidance by the American College of Obstetricians and Gynecologists (ACOG), the NHS, the CDC and the World Health Organization. Baby sizes are averages; your baby may be bigger or smaller and still perfectly healthy.
General information only, not medical advice.
History of updates
- : Added a weekly checklist and common questions.
- : Matched fruit, length and weight to the Prego app.
- : Published.