33 weeks pregnant
Your baby is about 44 cm and 1.9 kg; the bones are hardening.
At week 33, your baby’s bones are hardening, while the skull bones stay flexible to make birth easier. More antibodies pass from you to your baby.
This week’s ultrasound image
Expected ultrasound appearance and measurements at week 33 (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)
43.6 cm
Head diameter
85 mm
Head circumference
305 mm
Femur length
64 mm
Estimated weight
1918 g
Heart rate
136 bpm
UA PI
0.88
How big is your baby this week?
About the size of a honeydew melon
What can be seen on the ultrasound?
BPD is about 85 mm, HC about 305 mm, AC about 293 mm and FL about 64 mm. The estimated weight is around 1,900 grams.
Your baby’s development
Your baby is about the size of a honeydew melon. The immune system is developing; antibodies from you will keep protecting your baby after birth.
Changes in your body
Pelvic pressure and lower back and hip pain may increase. Numbness in the wrists (carpal tunnel syndrome) can occur.
Check-ups at this stage
- Routine check: blood pressure, weight, urine
- Tests to check your baby’s wellbeing (NST) if needed
- Birth plan and hospital registration
Tips for this week
- Wearing a wrist splint at night may help with wrist numbness
- A warm shower can ease lower back pain
- Rest often, even if only briefly
When should you see your doctor?
Contact your doctor if you have reduced baby movements, bleeding, leaking fluid, regular contractions, a severe headache, blurred vision or itching (especially on the palms).
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 is an NST?
A non-stress test is a painless test that records your baby’s heart rate and how it changes with movement; it is used to assess your baby’s wellbeing.
Why does itching matter in pregnancy?
Itching, especially on the palms and soles and worse at night, can be a sign of a liver condition called obstetric cholestasis; it should be checked with a blood test.
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