Second Trimester • 4 months

21 Weeks Pregnant: Baby Size, Symptoms & Due Date Milestones

Comprehensive gestational timeline analysis, fetal growth metrics, anatomical development, and personalized due date milestones for week 21.

Gestational Classification
At 21 weeks pregnant, you are in your Second Trimester

Equivalent to 4 months • 147 calendar days of gestation completed

Overall Gestational Progress 52.5% of 40 Weeks (147 of 280 Days)
Days Pregnant
147 Days
Exact duration
Days Until Due Date
133 Days
19.0 weeks left
Trimester Stage
2nd Trimester
Weeks 14 – 27
Fetal Size Category
Carrot
26.7 cm

Baby Development at 21 Weeks Pregnant

Baby Size Comparison
Carrot

Fruit / Vegetable Analogy

Estimated Length
26.7 cm

Crown to Heel (Total Length)

Estimated Weight
360 g

Fetal Weight Standard

At week 21, the baby's bone marrow takes over as the primary site of red blood cell production, relieving the liver and spleen of this workload. Bone marrow will remain the body's blood factory for the rest of life.

The baby's taste buds are functional and responsive. Flavors from maternal meals (such as garlic, curry, or sweet fruits) subtly flavor the amniotic fluid, beginning the baby's early introduction to dietary tastes.

Personalized Due Date Recalculator

Input your last menstrual period (LMP) to verify your exact week, remaining days, and estimated delivery date.

Real-Time Engine
Recalculated Due Date
Select your LMP date
Days Remaining
--
Current Gestation
--

Disclaimer: Computational estimates are based on standard clinical algorithms (e.g., Naegele's rule) for educational and planning purposes only. They do not constitute formal medical evaluation, diagnosis, or clinical obstetrics advice.

Disclaimer: Computational estimates are based on standard clinical algorithms (e.g., Naegele's rule) for educational and planning purposes only. They do not constitute formal medical evaluation, diagnosis, or clinical obstetrics advice.

Maternal Symptoms & Clinical Guidance at Week 21

Common Physical Symptoms

  • Pronounced rhythmic movements, flips, and sleep-wake cycles
  • Increased varicose veins or spider veins in legs
  • Mild braxton hicks contractions (painless uterine tightenings)
  • Frequent heartburn after spicy or acidic meals

Clinical Action Items

  • Wear graduated compression stockings if troubled by varicose veins
  • Elevate your feet on a footstool whenever sitting for extended periods
  • Maintain moderate daily walks to support venous blood return
  • Note the difference between painless Braxton Hicks and real labor

Navigate Pregnancy Timeline

Explore Second Trimester Weeks

Frequently Asked Questions About 21 Weeks Pregnant

Yes. Fetal taste buds are well-developed by week 21, and aromatic molecules from strong flavors in maternal food pass into the amniotic fluid, which the baby swallows throughout the day.