3rd TrimesterMonth 9Week 40 of 40
40 Weeks Pregnant
— How Many Months Is It?
40w
Equivalent to
Month 9
3rd Trimester
🍉
Baby is the size of a
Full-Grown Watermelon
51.2 cm (~20.2 in) · 3.4 kg
🌱Fetal Development Milestones — Week 40
Your official due date week! Delivery between weeks 38 and 42 is completely normal.
Pregnancy timeline progress100%
Week 1Week 40Week 40
Calculate Your Exact Due Date
Enter your last period date for an instant gestational calculation
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Enter your date to calculate gestational age.
Based on ACOG guidelines and Naegele's Rule for informational purposes only. Consult your OB-GYN.
Adjacent Pregnancy Weeks
Frequently Asked Questions — Week 40
40 weeks pregnant equals Month 9 of gestation in the 3rd Trimester. Because calendar months vary between 28 and 31 days while weeks are exactly 7 days, clinical tracking in weeks provides the most accurate timeline.
Your official due date week! Delivery between weeks 38 and 42 is completely normal.
Use the calculator above: enter the first day of your last period (LMP) and the tool will calculate your exact estimated due date using Naegele\'s Rule (LMP + 280 days).