The short answer
40 weeks = 9 months
At 40 weeks pregnant, you are about 9 months pregnant — in month 9 of your pregnancy and in your third trimester.
Not sure of your week? Use the pregnancy week calculator to find it from your last period, due date or conception date.
Due date week — though only about 1 in 20 babies actually arrives on the estimated date itself. Most come within two weeks on either side.
About the size of a small pumpkin
size comparison
51.2 cm
crown to heel (20.2 in)
3.4 kg
average weight (7.5 lb)
The skull bones are still soft and separated by fontanelles, allowing them to overlap slightly during birth — that is why newborn heads can look a little cone-shaped for a few days. Antibodies are still passing across the placenta and will offer some protection in the first months. Growth has slowed, but the fetus is still adding small amounts of fat.
Sizes and weights are averages — healthy babies vary widely, and your scan measurements are what count.
Reaching your due date without labor is very common and not a sign anything is wrong. Contractions may start and stop, and it can be hard to tell practice from the real thing until they become regular and stronger. Emotional exhaustion and impatience are normal.
Common symptoms this week
Week 40 sits 0 days past the 280-day mark, so there is no countdown left to run. Most babies arrive within two weeks either side of the due date, and your provider will be monitoring more closely from here.
Week 40 is full term and covers your estimated due date. Only about 1 in 20 babies is born on the date itself, so going a few days past it is completely normal rather than overdue.
The term labels are set by exact week and day, not by month: early term is 37 weeks 0 days to 38 weeks 6 days, full term is 39 weeks 0 days to 40 weeks 6 days, late term is 41 weeks 0 days to 41 weeks 6 days, and post-term is 42 weeks 0 days onward. All four fall inside "9 months pregnant", which is exactly why your care team never uses months for this.
A calendar month averages about 4.3 weeks — not 4 — so you can't just divide your week number by four. Instead, months of pregnancy are counted as uneven buckets of 4 to 5 weeks, arranged so the full 40 weeks fits into 9 calendar months. Week 40 falls in month 9, in the third trimester.
Your care team will always use weeks and days rather than months, because screening windows and term definitions are set by exact week — months are just the everyday shorthand. For the full conversion, see the weeks to months chart, or go the other way with the months-to-weeks guide.
Your notes will show a week and a day — 40+3 or 40w3d, for example. Pick the exact day you are on for its own day count, countdown and month answer.
| Week + day | Shorthand | Days pregnant | Days to go |
|---|---|---|---|
| 40 weeks 0 days (this page) | 40+0 | 280 | — |
| 40 weeks 1 day | 40+1 | 281 | — |
| 40 weeks 2 days | 40+2 | 282 | — |
| 40 weeks 3 days | 40+3 | 283 | — |
| 40 weeks 4 days | 40+4 | 284 | — |
| 40 weeks 5 days | 40+5 | 285 | — |
| 40 weeks 6 days | 40+6 | 286 | — |
At 40 weeks pregnant, you are about 9 months pregnant — in month 9 of your pregnancy and in your third trimester. Months of pregnancy are counted as uneven 4–5 week buckets so that the full 40 weeks fits into 9 calendar months.
40 weeks is in the third trimester, which runs from 28 weeks 0 days until birth. You are now considered full term from 39 weeks 0 days.
You have reached your due date week. Most babies arrive within two weeks either side of the due date, and your provider will discuss monitoring or induction if pregnancy continues past 41–42 weeks.
At 40 weeks you have passed the 280-day mark by 0 days, so there are no days left to count down. Most babies arrive within two weeks either side of the due date.
40 weeks is 280 days, counted from the first day of your last menstrual period (40 × 7 = 280). Add the days into your current week for the exact figure — for example 40 weeks 3 days is 283 days.