Second TrimesterWeek 17 of 40

Baby Gender Prediction at 17 Weeks

By 17 weeks, the genitalia are well-developed and gender prediction is highly reliable. Most parents who want an early gender reveal choose this window for their scan.

Your Baby at 17 Weeks

  • Baby is about 130mm — the size of a pear
  • Fat is beginning to develop under the skin
  • Baby's skeleton is changing from cartilage to bone

Gender Prediction Methods at 17 Weeks

Nub Theory

✓ Available~90%+ (direct observation)

At 17 weeks, the nub has evolved into clearly differentiated genitalia. Direct observation is now more relevant than nub theory, with ~90% accuracy.

Skull Theory

✓ Available~80-85%

Skull theory continues to give around 80% accuracy at 17 weeks and can supplement direct genital observation.

Chinese Gender Calendar

✓ Available~50-70% (varies by study)

The Chinese Gender Calendar remains a popular cultural method — especially in Asian families — though it's less accurate than ultrasound techniques.

AI Ultrasound Analysis

✓ Available~85-90%

AI analysis at 17 weeks reaches around 88-90% accuracy by examining the now-visible external genitalia alongside skull and body position markers.

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Frequently Asked Questions

Can you tell the gender of a baby at 17 weeks?

Absolutely — 17 weeks is a reliable time to predict gender. The external genitalia are clearly developing and most methods achieve 85-90% accuracy.

How accurate is gender prediction at 17 weeks?

Around 88-90% from AI and direct genital observation, 80% from skull theory. 17 weeks is an excellent time for a confident early prediction.

What does a boy/girl look like on an ultrasound at 17 weeks?

At 17 weeks, male genitalia is clearly visible — the scrotum, penis, and testes (which are descending) are all developing. Female genitalia shows well-defined labia.