Fetal Milestone Calculator — Track Pregnancy Week by Week

Fetal Milestone Calculator

Track fetal development week by week. Calculate baby size, weight milestones, and see comparisons to everyday objects throughout pregnancy.

Step 1: Pregnancy Details

20 weeks
6.5 inches
First Trimester Week 20 Third Trimester

Understanding Fetal Development

Fetal development follows predictable patterns. By week 20, most organs are formed. The baby can hear sounds and is developing taste buds. Movement becomes more coordinated.

Step 2: Calculation Options

Key Developmental Stages

Weeks 4-12: Organ formation, heartbeat begins
Weeks 13-27: Rapid growth, movement felt
Weeks 28-40: Final development, weight gain
Average pregnancy: 40 weeks (280 days)

Fetal Development Results

Development Summary
Size Comparisons
Weekly Milestones

Fetal Size at 20 Weeks

6.5 inches
Approx. 10.6 ounces
Length (Crown to Rump)
6.5 in
Estimated Weight
10.6 oz
Trimester
Second
Days Pregnant
140 days

Size Comparison to Everyday Objects

Object Size Comparison Visual Reference

Weekly Developmental Milestones

Current Week: 20

The baby is about the size of a banana. Vernix caseosa (a creamy protective coating) covers the skin. The baby can hear sounds and may respond to loud noises with movement.

Next Week: 21

The baby’s digestive system is active, producing meconium. Bone marrow starts making blood cells. Eyebrows and eyelids are fully formed.

Previous Week: 19

A protective coating called vernix begins to form on the skin. The baby’s kidneys are making urine. Hair is starting to sprout on the scalp.

Key Upcoming Milestones

Week 24: Viability milestone – baby could survive outside womb with medical care
Week 28: Third trimester begins – rapid brain development
Week 32: Baby practices breathing – lungs developing
Week 37: Considered full term – organs ready for life outside

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