4 weeks pregnant: baby is the size of a poppy seed
At 4 weeks, baby is about the size of
a poppy seed
The embryo has just settled into the womb. Many people find out they're pregnant around now.
- Length1 mm (0.04 in)
- Weightless than 1 g
- Trimester1 of 3
Baby is measured from head to bottom (crown to rump) at this stage. These are rounded averages. Your ultrasound is the only real measurement of your baby.
Questions moms ask
How big is a baby at 4 weeks?
At 4 weeks, baby is about the size of a poppy seed: around 1 mm (0.04 in) long from head to bottom (crown to rump), and weighs about less than 1 g. Every baby grows at their own pace.
What trimester is 4 weeks?
4 weeks is in the first trimester.
How many months pregnant is 4 weeks?
Roughly month 1 of 9.
Related tools
This page gives estimates, not medical advice. If you're worried about your baby's growth, talk to your doctor or midwife.