Second trimester
21 weeks pregnant
The fetus is around the size of a carrot and now measured from head to heel rather than head to bottom, which makes the length jump sharply this week. Movements are strong and increasingly obvious to you.
Size of
carrot
Length
27 cm
Weight
360 g
Your baby at 21 weeks
Measurement convention changes around now from crown-rump to crown-heel, which is why the numbers appear to leap. Nothing unusual has happened.
The digestive system is practising: the fetus swallows amniotic fluid, absorbs water from it, and passes the remainder into the bowel as meconium.
Bone marrow begins producing blood cells, a job previously handled by the liver and spleen.
How you may be feeling
Movements are usually unmistakable and may be visible from outside. Partners can often feel them by placing a hand on the bump, though the fetus has a reliable habit of stopping the moment anyone tries.
Stretch marks may appear on the abdomen, breasts or thighs. They are largely determined by genetics and skin elasticity rather than anything you do, though keeping skin moisturised helps with the itching.
Common symptoms around week 21
- Strong, visible movement
- Stretch marks appearing
- Itchy skin over the growing bump
- Heartburn and indigestion
- Increased appetite
Appointments and tests around now
Appointments are typically monthly at this stage in an uncomplicated pregnancy, with fundal height, blood pressure and urine checked each time.
What is normal, and what varies
Stretch marks are extremely common and largely genetic. Creams may ease itching and improve comfort, but no product reliably prevents them, and their appearance is not a reflection of how well you have looked after yourself.
Worth doing this week
Take severe itching seriously
Generalised itching without a rash, worst on the palms and soles and at night, can signal obstetric cholestasis. It is easily checked with a blood test and worth raising promptly.
Moisturise for comfort
It will not prevent stretch marks, but it does help with the itching that comes from skin stretching.
Invite your partner to feel
Movements are usually palpable from outside now, which for many partners is the moment the pregnancy becomes real.
Looking ahead
Next week the fetus looks much like a newborn in miniature, and grip strength develops.
Nearby weeks
Not sure which week you are in? The week tracker works it out from the first day of your last period, and the due date calculator gives you an estimated due date.