Week 40 of pregnancy
40 Weeks Pregnant
Third trimester
Baby size
About the size of a small pumpkin
51.2 cm
What's developing
This is your estimated due date. Only about 1 in 20 babies actually arrive on this day — most come a bit before or after.
Common symptoms this week
- Contractions
- Water breaking possible
- Backache
- Cervical dilation
This is an estimate for information only — only about 1 in 20 babies arrive on their due date. Always confirm dates with your midwife or doctor.
How big is a baby at 40 weeks?
Baby growth chart
Typical fetal length and weight from week 8 to week 40.
Length
cmWeek 40: 51.2 cm
Weight
gramsWeek 40: 3.46 kg
Typical averages based on Hadlock / ACOG references. Weeks 8–20 use crown–rump length; weeks 21–40 switch to crown–heel — that's the small jump you'll see mid-chart. Real babies vary — your ultrasound is the reliable number for you.55
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