Second trimester · Week 17 of 40

Pregnancy week 17

Fat stores begin; the skeleton keeps hardening.

Approx. length13.0 cm
Approx. weight140 g
Size feelpear
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Baby development at week 17

Adipose tissue starts for temperature regulation later. Sweat glands form. The skeleton continues replacing cartilage with bone.

Average size estimates for week 17 are about 13.0 cm and 140 g — roughly pear. Your ultrasound report and clinician’s dating override any website average.

What you might feel

You may feel more “pregnant” in your center of gravity. Supportive shoes and slower sit-to-stand habits help.

You are in the second trimester. Two pregnancies at the same week can feel completely different — treat these notes as orientation, not a checklist you must match.

What to track this week

A calm next step in Preglo

Track water more intentionally as blood volume rises — Preglo’s goal dial keeps it frictionless.

Also useful: due date calculator · all weeks · Preglo features

Nearby weeks: Week 15 · Week 16 · Week 18 · Week 19

Educational averages only — not medical advice. Contact your clinician for symptoms that worry you, bleeding, severe pain, or reduced movements.

Week 17 FAQ

How big is the baby at week 17?

Typical educational averages are about 13.0 cm long and 140 g. Individual growth and measurement methods vary.

Which trimester is week 17?

Week 17 is generally counted in the second trimester (weeks 1–12 first, 13–27 second, 28–40 third in common educational grouping).

Should I track anything special this week?

Track water more intentionally as blood volume rises — Preglo’s goal dial keeps it frictionless.

Preglo

Track this week in Preglo.

Week tracker, kick counter, water log, and widgets — private on iPhone.

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