39 weeks pregnant
Full term: your baby is about 50 cm and 3.3 kg.
Week 39 marks the start of full term. Your baby is ready to be born and keeps gaining weight in these final weeks.
This week’s ultrasound image
Expected ultrasound appearance and measurements at week 39 (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)
Length (head to heel)
50 cm
Head diameter
94 mm
Head circumference
336 mm
Femur length
73 mm
Estimated weight
3288 g
Heart rate
133 bpm
UA PI
0.76
How big is your baby this week?
About the size of a small watermelon
What can be seen on the ultrasound?
BPD is about 94 mm, HC about 336 mm, AC about 344 mm and FL about 73 mm. The amniotic fluid and placenta are assessed if needed.
Your baby’s development
Your baby is about the size of a small watermelon. Fat tissue helps them keep warm. The brain will continue to develop rapidly after birth.
Changes in your body
Impatience, sleeplessness and tiredness are normal. Irregular tightenings may turn into real contractions.
Check-ups at this stage
- Weekly check: blood pressure, weight, urine
- NST and ultrasound if needed
- Discussing next steps if labour does not start
Tips for this week
- Balance gentle walks with rest
- Share the signs of labour with the people close to you
- Make time for little things you enjoy
When should you see your doctor?
Go to the hospital if your waters break, or if you have bleeding, regular contractions, reduced baby movements, a fever, a severe headache or blurred vision.
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
What are the signs of labour?
The most common signs are regular contractions that get closer together, your waters breaking and a bloody show. Lower back pain and pressure in the groin may also occur.
Is there a way to start labour naturally?
Suggestions such as walking have limited effect. If labour needs to be started (induction), your doctor will plan safe methods with you.
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