Digestive & Metabolic System

Liver Development & Function

Liver develops early and performs multiple vital functions including blood production.

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Development Timeline

Weeks 4-40

Overview

The liver is one of the first organs to develop and one of the largest in the fetal body. It performs many critical functions during pregnancy, quite different from its adult role.

In fetuses, the liver is the main blood-producing organ from weeks 8-24. It also filters blood, stores nutrients, produces proteins, and processes bilirubin. The liver is disproportionately large in fetuses - about 10% of body weight.

After birth, bone marrow fully takes over blood production, and the liver transitions to its adult functions. Jaundice in newborns occurs when the immature liver can't process bilirubin quickly enough.

🗓️ Week-by-Week Milestones

Week 4

Liver tissue beginning to form

Week 6

Liver recognizable

Week 8

Liver producing blood cells

Week 12

Liver visible on ultrasound

Week 24

Bone marrow gradually taking over blood production

Week 32

Liver storing nutrients

Week 36

Liver preparing for postnatal functions

👀 What to Expect

•Liver seen on anatomy scan
•Disproportionately large in fetus
•Critical for fetal survival and growth
•Transitions to adult functions after birth
•May cause jaundice in first week
•Functions improve rapidly in first weeks

💡 Tips for Parents

✓Liver is one of the largest fetal organs
✓Ultrasounds check liver size and position
✓Liver produces blood during pregnancy
✓Newborn liver still immature (causes jaundice)
✓Takes time for liver to fully mature after birth
✓Your liver does much of the filtering for baby

✨ Amazing Facts

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Fetal liver makes blood cells

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In fetuses, liver is about 10% of body weight

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In adults, liver is only 2-3% of body weight

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The liver is the only organ that can regenerate

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Stores iron from mother for first months of life