2nd trimester · Week 21
21 weeks pregnant
Bone marrow and more swallows
Bone marrow takes a larger role in making blood cells. Swallowing practice increases. Your appetite and heartburn may both rise.
How big is your baby at 21 weeks?
- Length
- 26.7 cm
- Weight
- 360 g
- Size
- Apple
On average about 26.7 cm long and 360 g. Size comparison: Apple.
These are averages; every baby grows at their own pace.
How is your baby developing at 21 weeks?
Eyebrows are faint. The fetus can reach the umbilical cord. Average crown–heel length is about 27 cm; weight often near 360 g. Lungs are not ready to work in air.
What changes in your body at 21 weeks?
Braxton Hicks, stretch marks, and a sharper hunger can appear. Leg cramps at night are common. Balance may feel slightly off.
Tips for this week
A snack and calf stretch before bed help some cramps; persistent one-sided calf pain and swelling needs urgent review for a clot. Sleep slightly propped if heartburn wakes you. Avoid lying flat if you feel breathless or dizzy.
