3rd trimester · Week 40
40 weeks pregnant
The due date is an estimate
The due date is a midpoint, not a deadline. Many healthy pregnancies continue to 41 weeks with extra checks. Term is 37–42 weeks; your clinician will discuss induction if you go past the local cutoff.
How big is your baby at 40 weeks?
- Length
- 51.2 cm
- Weight
- 3,460 g
- Size
- Watermelon
On average about 51.2 cm long and 3,460 g. Size comparison: Watermelon.
These are averages; every baby grows at their own pace.
How is your baby developing at 40 weeks?
Average length is about 51 cm and weight often near 3.4–3.5 kg, with a wide healthy range. The skull stays moldable. Meconium should usually stay in the gut until after birth.
What changes in your body at 40 weeks?
You may feel done — that is emotional, not a medical diagnosis of labor. The cervix can be favorable or still closed. Swelling that is sudden, especially with headache, still needs review.
Tips for this week
Ask what post-dates monitoring looks like (CTG, ultrasound, membrane sweep offers). Do not use castor oil or unprescribed herbs to force labor. Go in for reduced movements, waters breaking (especially if green or foul), heavy bleeding, or regular painful contractions per your hospital’s guidance. This remains general information.
