Day 28 of 280 · 4 weeks
Poppy seed
Last reviewed · 3 min read · 6 sources · Plain-text version
Four weeks today. Your baby is about 2 mm, about the size of a poppy seed, and today you put one on a plate and look.
- Size this week
- about the size of a poppy seed
- Length this week
- about 2 mm from head to bottom

Four weeks today, counted from the first day of your last period. This is the week the NHS's week-by-week guide begins, and with it the first size you can hold in your hand.
Your baby

"Your baby, or embryo, is about 2mm long (about the size of a poppy seed) and growing rapidly in your womb" (NHS). It is protected by a fluid-filled amniotic sac and attached to a yolk sac that supplies its nourishment (NHS). The outer layer of cells will later become the placenta, which provides oxygen and nutrients (NHS).
You are in the first trimester, weeks 1 to 12 (NICHD).
Your body
Pregnancy is dated from the first day of your last period, which is why "4 weeks" arrives about two weeks after conception (NHS). Some home tests can detect pregnancy from about 3½ weeks (NHS), so this may be the week a line appears, or the week your period doesn't.
You probably won't look pregnant yet: first pregnancies often don't show until about week 12, though later pregnancies may show sooner (NHS). What you may notice instead is on the NHS's list of common early symptoms: a missed period, nausea, tiredness, sore breasts, needing to pee more often, bloating, cramping (NHS). You may also have no symptoms at all (NHS).
Try today
The poppy-seed picture
Time: 2 minutes, at the kitchen table
Put one poppy seed on a white plate (NHS).
Look at it in good light. That is about 2 mm, the NHS's size for this week (NHS).
Take a photo of the plate. It's the first page of a record, and it is allowed to be the only thing in the frame.
If you have a partner, hand them the plate. It is easier to believe than a line on a test.
Make it work:No poppy seeds in the house? The 2 mm mark on a ruler does the same job (NHS).
Watch for
Normal
mild cramping and bloating, both on the NHS's list of common early symptoms (NHS).
Call your provider right away
for pain with bleeding, or belly or pelvic pain; if you can't reach them, go to the emergency room (MedlinePlus).
Normal
light spotting 10 to 14 days after conception, if it's light and brief (MedlinePlus).
Call your provider right away
for any bleeding in the first 3 months, because it may indicate miscarriage or ectopic pregnancy (MedlinePlus).
Normal
needing to pee more often (NHS).
Go to the ER
for dizziness or fainting; the CDC lists both as urgent warning signs during pregnancy (CDC).
For you
If you're reading this later, after a test in week 5 or 6, this is the week you probably spent waiting without knowing it. Many people learn they're pregnant around week 5, often after a late period (NHS). The poppy seed was there either way.
Nobody can see anything yet (NHS), which means today is yours to keep or to share. Both are fine.
If you're the partner: this is the week to start looking at the plate instead of at her for signs. There aren't any to see, and she doesn't need to be watched.
Sources
- NHS. "Week 4." Week-by-week guide to pregnancy, Best Start in Life. https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-4/
- National Institute of Child Health and Human Development. "About Pregnancy." National Institutes of Health. https://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo
- MedlinePlus. "Vaginal bleeding in early pregnancy." National Library of Medicine. https://medlineplus.gov/ency/patientinstructions/000614.htm
- MedlinePlus. "Vaginal bleeding in pregnancy." Medical Encyclopedia, National Library of Medicine. https://medlineplus.gov/ency/article/003264.htm
- Centers for Disease Control and Prevention. "Urgent Maternal Warning Signs and Symptoms." HEAR HER campaign, 2024. https://www.cdc.gov/hearher/maternal-warning-signs/index.html
- NHS. "Week 5." Week-by-week guide to pregnancy, Best Start in Life. https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-5/
This guide is general education that summarizes published research and guidance from groups like the American Academy of Pediatrics, the CDC, and the WHO. It isn’t medical advice, and every child develops on their own timeline. Your pediatrician knows your child; if something feels wrong, call them. In an emergency, call 911.
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