What pregnancy week 40 means
Estimated due date. “40 weeks pregnant” means 40 weeks have passed since the first day of the last menstrual period — the standard way pregnancy is dated. Conception usually happened about two weeks after that date, so the baby’s own age (fetal age) is roughly 38 weeks. Week 40 runs from 40 weeks 0 days to 40 weeks 6 days; on the following day the pregnancy is 41 weeks.
Your baby at 40 weeks
The baby is fully developed. Average birth weights are around 3.4 kg (7.5 lb), but healthy babies are born across a wide range of sizes.
A common way to picture it: the baby is now about the size of a watermelon — roughly about 51 cm and about 3.4 kg. These are averages; babies grow at different rates, and ultrasound measurements vary.
Your body at 40 weeks
You have reached your estimated due date. Only a small proportion of babies arrive on the due date itself; many first babies come a little later. Feeling impatient or anxious is completely understandable.
Care and appointments around week 40
If labour has not started, your provider will usually discuss monitoring and the timing of a possible induction over the coming week or two.
The timing of tests and appointments differs between countries and care providers. If anything worries you — such as bleeding, severe pain, fluid leaking, fever, or a change in your baby’s movements — contact your midwife, doctor or maternity unit straight away rather than waiting for your next appointment.
Week 40 in your pregnancy timeline
Week 40 is in the third trimester (weeks 28–40+) and in pregnancy month 9, which covers roughly weeks 36–40. You have reached full term.
| Pregnancy start (first day of last period) | |
|---|---|
| Estimated conception | |
| Estimated due date (40 weeks) |
Dates assume you are exactly 40 weeks 0 days today. For dates based on your own last period, use the calculator above or the main Pregnancy Calculator.
40 weeks pregnant in days and months
40 weeks is 280 days of pregnancy — 100% of a 40-week pregnancy. Counted in calendar months, 40 weeks is about 9.2 months, which is usually described as month 9 of pregnancy. Months are only a rough grouping; healthcare professionals almost always talk in weeks and days because they are more precise. See Pregnancy Month Calculator for how weeks map to months.