23 weeks pregnant
Your baby is about 29 cm and 500 grams; the lungs start to prepare for breathing.
At week 23, your baby reaches half a kilogram. The structures in the lungs that will make breathing possible begin to develop.
This week’s ultrasound image
Expected ultrasound appearance and measurements at week 23 (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)
28.9 cm
Head diameter
56 mm
Head circumference
210 mm
Femur length
41 mm
Estimated weight
501 g
Heart rate
142 bpm
How big is your baby this week?
About the size of a grapefruit
What can be seen on the ultrasound?
BPD is about 56 mm, HC about 210 mm, AC about 188 mm and FL about 41 mm. The heart rate is about 140–145 beats per minute.
Your baby’s development
Your baby is about the size of a grapefruit. Small blood vessels and air sacs are developing in the lungs. Your baby may react to loud noises and respond with movements.
Changes in your body
Mild swelling of the feet and hands, bleeding gums and needing to pass urine more often are common.
Check-ups at this stage
- Routine check: blood pressure, weight, urine
- Booking the glucose tolerance test for weeks 24–28
- Blood count (to check for iron deficiency)
Tips for this week
- Cut down on salt and drink plenty of water; this helps reduce swelling
- Take off rings and tight shoes if they feel too tight
- Talk to your baby and play music; they can hear sounds
When should you see your doctor?
Contact your doctor if you have sudden, marked swelling of the face or hands, a severe headache, blurred vision, bleeding or regular contractions.
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
Are swollen feet normal in pregnancy?
Mild ankle swelling at the end of the day is common. However, sudden swelling of the face and hands with a headache and blurred vision must be checked straight away for pre-eclampsia.
Can the baby hear sounds?
Yes. Around week 23, your baby starts to react to outside sounds, especially your voice and loud noises.
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