👶Your baby this week
Your baby is now about the length of a full sized baby bottle, roughly 26.7 cm from head to heel and is entering a rapid growth phase.
Measurements are now crown-to-heel, so it may seem like your baby has had a sudden growth spurt compared with earlier weeks.
Movements are more coordinated as arms and legs are now in proportion; you may notice more distinct kicks, stretches and rolls.
Baby is practising life-ready skills: swallowing small amounts of amniotic fluid, breathing-like motions and strengthening the sucking reflex.
Taste buds are active, so flavours from your meals subtly season the amniotic fluid.
Hearing is improving, voices and everyday sounds outside the womb can be detected.
Lanugo (a fine downy hair) covers the body to help with temperature regulation; eyebrows and scalp hair are developing.
The placenta keeps growing to fuel your baby; by now, baby typically weighs more than the placenta.
Bone marrow begins contributing to blood cell production alongside the liver and spleen.
🌸Your body this week
As the second half of pregnancy begins, your bump grows quickly and you may feel a little unsteady, loosened joints and a shifted centre of gravity are normal.
Baby’s sleep/wake cycles are forming and might not match your own, which can make night-time sleep trickier.
Skin may continue to stretch, with new or changing stretch marks on the tummy, hips, breasts or thighs.
Backache and round-ligament twinges can persist as the uterus expands.
Some people notice a stronger appetite and faster hair/nail growth due to hormones and increased circulation.
💛Symptoms you might notice
Every pregnancy is different. These are common around week 21 — speak to your midwife if anything worries you.
Sleep Disruption
Active baby, nasal stuffiness or aches can make sleep harder. Side-sleeping with pillows between knees and under the bump can help.
Backache
A growing bump shifts posture and relaxin loosens joints. Use supportive footwear, keep good posture and consider a prenatal massage.
Heartburn & Indigestion
Eat smaller, frequent meals, avoid late heavy dinners and stay upright after eating to reduce reflux.
Bloating & Constipation
Drink water, add fibre (wholegrains, fruit, veg, beans) and stay active to keep things moving.
Headaches or Dizziness
Common in warm, stuffy rooms or when dehydrated. Take fresh-air breaks, hydrate and rise slowly from sitting.
Bleeding Gums
Hormonal changes can inflame gums. Brush gently twice daily, floss, and arrange a dental check-up (NHS dental care is free in pregnancy).
Leg Cramps
Often strike at night. Gently flex toes toward the shin, massage calves and stretch before bed.
✨Tips for week 21
Safety on the Move
If using public transport, consider a “baby on board” badge to encourage seats. If you do take a tumble, baby is well cushioned, but let your midwife know.
Whooping Cough Vaccine
If you haven’t had it yet, the pertussis (whooping cough) jab is recommended between weeks 16–32. Immunity passes to your baby via the placenta.
Nourish You Both
Dump the junk: aim for 5-a-day fruit & veg, wholegrains, lean proteins and lower-sugar options. Simple swaps (e.g., homemade versions of favourites) boost energy and nutrition.
Pelvic Floor Exercises
Do daily squeezes (as if stopping mid-wee) to strengthen muscles and help prevent leaks later in pregnancy and after birth.
Stay Active (Comfortably)
Target ~150 minutes/week of gentle to moderate activity (walking, swimming, prenatal yoga). Avoid high impact moves if joints feel unstable.
Rest Smart
Power naps can offset broken nights. Build a wind-down routine with light stretches or ‘beditation’ to help you drift off.
Vitamin D & Supplements
Continue a daily 10-microgram vitamin D supplement (especially Oct–Mar), plus folic acid if advised. Avoid alcohol, smoking and limit caffeine.
Work & Rights
When you tell your employer about the pregnancy, you are entitled to paid time off for antenatal care and a workplace risk assessment.
When to Seek Help
Contact a midwife or maternity unit urgently for severe pain, heavy bleeding, persistent severe headache, visual changes, sudden swelling or reduced/no movements after 24 weeks.