Your baby at 21 weeks
Your baby is the size of a large banana. Your baby weighs between 284 and 368 g (10 and 13 oz) and is around 22.8 cm (9 inches) long.
Your baby’s heartbeat is now loud enough to be heard through a simple stethoscope, but the beat can be difficult to distinguish from your own. Listen for the faster rhythm: Your baby's heartbeat is 120 to 160 beats per minute, about twice as fast as your own.
Baby is already starting to sleep and wake in subtle cycles. Ultrasounds show that unborn babies may even settle into a favourite sleeping position.
Your pregnancy at 21 weeks
Backaches, especially in the lower back, are quite common during pregnancy. Your growing uterus is shifting your centre of gravity and pulling your lower back forwards. Meanwhile, the hormone relaxin is loosening every joint and ligament in your body, which will allow your pelvis to expand when it’s time for delivery.
Whenever you sit, whether you're watching television or working, use a footrest to elevate your feet slightly. If you need to stand for a long period of time, alternate putting one foot on a small stool to take some pressure off your lower back. Treat yourself to a warm bath for additional relief. If your back pain continues, give your healthcare provider a call.
Did you know?
Baby already has sleep/wake cycles in your uterus and even at 21 weeks, still has plenty of room to move around. When you’re awake and active, your movement keeps the baby rocked to sleep; but when you want to sleep, baby may wake up and start dancing! All of these movements are important for developing the muscles and nerve pathways to baby’s brain.