Second Trimester
Week 21: Baby
Here's everything happening with your baby and your body this week.
Your baby is the size of a
Carrot
Length
10.5 in
Weight
360 g
Week
21 / 40
💡 Expert tip
Iron-rich foods are critical now — red meat, lentils, fortified cereals, and spinach. Pair with vitamin C to boost absorption.
🌱 Baby's development this week
- Movements strong enough for others to feel
- Bone marrow beginning to produce blood cells
- Liver and spleen busy producing blood cells
- Skin still translucent — blood vessels visible
Science fact
If the baby is female, her ovaries already contain approximately 6–7 million eggs (oogonia) by week 20, more than she will ever have again. This number naturally declines to 1–2 million by birth and around 300,000 by puberty — a process called atresia.
🤰 Your symptoms this week
Leg cramps at night
common from mineral depletion and circulation changes
Increased back pain as uterus expands
support belt may help
Prenatal yoga, a support pillow, and swimming all help. Avoid standing for long periods.
Skin itching over abdomen
normal as skin stretches; see doctor if severe or widespread
💛 Changes in your body
- Belly button stretch marks may appear
- Varicose veins possible from increased blood volume
- Braxton Hicks contractions may begin
- Iron needs increasing significantly
💙 Mental health this week
Feeling baby move regularly creates a profound bond. If you notice a sudden decrease in movement, contact your provider — don
🥗 Nutrition focus
- Iron 27mg/day — your blood volume has increased 40–50% and baby needs iron stores
- Vitamin C with iron-rich foods maximizes absorption — orange juice, bell peppers, kiwi
- Magnesium-rich foods (nuts, seeds, whole grains) reduce leg cramps and improve sleep
📅 Appointment / test
If anatomy scan wasn
✅ This week's checklist
Start practicing kick-counting awareness — get to know your baby
,
,
Track your pregnancy week by week
Interactive guide · 40 weeks · Fruit size visualizations · Personalized tips
Open Week 21 in Interactive Guide → →