Week 4 of pregnancy
Week 4 is early days: much of what happens now is too small to see, and you may be the only one who knows.
About the size of a poppy seed
| Size | About a poppy seed |
|---|---|
| Length | 0.1 cm (0.04 in), measured from the top of the head to the bottom (crown to rump), the way early scans measure |
| Trimester | First trimester |
| Weeks to go | About 36 to your due date |
These are averages. Every baby grows at their own pace.
What is forming this week
A tiny ball of cells has settled into the lining of the womb and started to grow.
How you may feel
Many people feel nothing yet, and a late period is often the first sign.
Everyone's pregnancy is different. If something worries you, call your midwife or doctor.
One thing to do this week
Note the first day of your last period. Your midwife will ask for it.
Questions you could bring to your next appointment
- When is my dating scan, and what will it check?
- Which medicines and supplements are fine to keep taking?
- Who do I call if I'm worried between appointments?
- NHS: Your pregnancy week by week
- ACOG: How your fetus grows during pregnancy
- Hadlock FP et al. In utero analysis of fetal growth: a sonographic weight standard. Radiology 1991 (weights from week 10)
- Robinson HP, Fleming JE. A critical evaluation of sonar crown-rump length measurements. Br J Obstet Gynaecol 1975 (early lengths)
Questions
When is the first scan?
In England the NHS offers a dating scan between 10 and 14 weeks. In the US the timing of the first ultrasound depends on your care team, so ask at your first appointment.
Why is pregnancy counted from my last period?
Weeks are counted from the first day of your last period, about two weeks before conception. That is why week 4 is only around two weeks after conception.
Is my baby exactly this size?
No one is. The size, length and weight here are averages from published growth charts. Your scan results are the ones that count, and your midwife or doctor is the person to ask about them.
Start with today
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