17 weeks pregnant
Your baby is about 13 cm and 140 grams; fat tissue starts to form.
At week 17, your baby’s skeleton continues to change from cartilage to bone, and the first fat tissue forms under the skin.
This week’s ultrasound image
Expected ultrasound appearance and measurements at week 17 (illustrative, to-scale drawing).
Abbreviations on the screen
- GS
- Gestational sac diameter
- YS
- Yolk sac
- CRL
- Crown–rump length
- NT
- Nuchal translucency
- BPD
- Biparietal diameter (head width)
- HC
- Head circumference
- AC
- Abdominal circumference
- FL
- Femur (thigh bone) length
- EFW
- Estimated fetal weight
- FHR
- Fetal heart rate (beats per minute)
- GA
- Gestational age (weeks + days)
- UA PI
- Umbilical artery Doppler resistance (PI)
Crown–rump length
128 mm
Head diameter
38 mm
Head circumference
139 mm
Femur length
24 mm
Estimated weight
140 g
Heart rate
150 bpm
How big is your baby this week?
About the size of a pear
What can be seen on the ultrasound?
BPD is about 38 mm, HC about 139 mm and FL about 24 mm. The umbilical cord thickens, and its blood vessels can be seen with colour Doppler.
Your baby’s development
Your baby is about the size of a pear. Sucking and swallowing reflexes are developing. Sweat glands begin to form.
Changes in your body
As your womb grows, your centre of gravity shifts and back pain may start. Your appetite continues to increase.
Check-ups at this stage
- Routine check: blood pressure, weight, urine
- Preparing for the anomaly scan (weeks 18–22)
- Thyroid and iron checks if needed
Tips for this week
- Avoid heavy lifting; bend your knees when picking things up
- Sleep on your side; the left side supports circulation
- Pregnancy exercises and swimming can help with back pain
When should you see your doctor?
Contact your doctor if you have bleeding, regular contractions, fluid leaking from the vagina or severe abdominal pain.
Growth by week
Values are averages; differences of a few days or a few millimetres between babies are normal.
| Pregnancy weeks | Crown–rump length (cm) | Weight (g) |
|---|---|---|
| Week 4 | — | — |
| Week 5 | — | — |
| Week 6 | 4 mm | — |
| Week 7 | 10 mm | — |
| Week 8 | 16 mm | 1 g |
| Week 9 | 23 mm | 2 g |
| Week 10 | 32 mm | 4 g |
| Week 11 | 43 mm | 8 g |
| Week 12 | 55 mm | 14 g |
| Week 13 | 68 mm | 23 g |
| Week 14 | 85 mm | 43 g |
| Week 15 | 100 mm | 70 g |
| Week 16 | 115 mm | 100 g |
| Week 17 | 128 mm | 140 g |
| Week 18 | 140 mm | 190 g |
| Week 19 | 152 mm | 240 g |
| Week 20 | 25.6 cm | 300 g |
| Week 21 | 26.7 cm | 360 g |
| Week 22 | 27.8 cm | 430 g |
| Week 23 | 28.9 cm | 501 g |
| Week 24 | 30 cm | 600 g |
| Week 25 | 31.9 cm | 660 g |
| Week 26 | 33.8 cm | 760 g |
| Week 27 | 35.6 cm | 875 g |
| Week 28 | 37.5 cm | 1005 g |
| Week 29 | 38.8 cm | 1153 g |
| Week 30 | 40 cm | 1319 g |
| Week 31 | 41.3 cm | 1502 g |
| Week 32 | 42.5 cm | 1702 g |
| Week 33 | 43.6 cm | 1918 g |
| Week 34 | 44.8 cm | 2146 g |
| Week 35 | 45.9 cm | 2383 g |
| Week 36 | 47 cm | 2622 g |
| Week 37 | 48 cm | 2859 g |
| Week 38 | 49 cm | 3083 g |
| Week 39 | 50 cm | 3288 g |
| Week 40 | 51 cm | 3462 g |
Frequently asked questions
Is lying on my back harmful?
Later in pregnancy, lying flat on your back for long periods can put pressure on the major blood vessels. Lying on your side, especially the left side, is more comfortable and safer.
How much weight should I have gained by week 17?
It depends on your starting weight; a gain of 2–4 kg on average is common. Agree on the right target for you with your doctor.
Your pregnancy care at SoftCare Clinic
Book an appointment with our specialist doctors for your ultrasound check-up and any questions you may have.
The information on this page is for general guidance only and does not replace a medical examination. Measurements are average values; please discuss your own results with your doctor.
Medical content editor: Op. Dr. Şükrü Sanus