17 Weeks Pregnant — Baby Is the Size of a Turnip
At 17 weeks you are 119 days into the 40-week count, with 161 days to go and 43% of the pregnancy behind you. Baby is about the size of a turnip and weighs about 4.5 g. This page fixes week 17 in place: what is developing, which appointments are still ahead, and how the week maps onto months.
43% of 280 days. The due date itself is a midpoint, not a deadline: full-term births spread across roughly weeks 37 to 42.
This week
Fat tissue begins to form and baby starts to practice a sucking reflex with its thumb.
Measured in months, week 17 sits in month 4: Month four is the quiet stretch — the bump is visible to you, quickening may start, and the anatomy scan is booked.
Appointments still ahead
| Window | Appointment | What it checks |
|---|---|---|
| 18–22 wks | Anatomy scan | Detailed look at baby's organs, limbs and growth — often the sex reveal. |
| 24–28 wks | Glucose tolerance test | Screens for gestational diabetes. |
| 28–34 wks | Routine growth checks | Regular midwife visits, bump measurements and blood pressure. |
| 34–36 wks | Group B strep swab | A simple swab that protects the baby during delivery. |
| 37–40 wks | Weekly checkups | Position checks, growth checks and the birth plan in earnest. |
Around week 17
| Week | Size | Weight |
|---|---|---|
| 16 | an avocado | about 3.5 g |
| 17 | a turnip | about 4.5 g |
| 18 | a bell pepper | about 5.7 g |
Frequently asked
What does 17 weeks pregnant mean in days and months?
17 weeks is 119 days since the first day of your last period, which is about 4 months pregnant on the four-week-per-month convention. 161 days remain in the 40-week count from here — that is 43% of the way through.
How big is a baby at 17 weeks?
Around the size of a turnip, at about 4.5 g. These are population averages: a scan measurement that differs by a few days is normal and does not by itself mean anything is wrong.
Which trimester is week 17?
The 2nd trimester. The split used here is the same one the calculator applies: the first trimester covers days 1–90, the second 91–195, and the third from day 196 onward. Other sources draw the boundary a week either side, which is why week 13 and week 14 can both be described as "end of the first trimester".
What appointments happen after week 17?
Next up: Anatomy scan at 18–22 weeks, Glucose tolerance test at 24–28 weeks, Routine growth checks at 28–34 weeks. The full schedule is in the table above; exact timing varies by country and by your care team.