6 weeks pregnant
The embryo can be seen for the first time; the heartbeat is often visible this week.
Week 6 is an exciting time: the embryo can be seen on ultrasound for the first time, and the heartbeat is often visible.
This week’s ultrasound image
Expected ultrasound appearance and measurements at week 6 (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)
Gestational sac
13 mm
Crown–rump length
4 mm
Heart rate
112 bpm
How big is your baby this week?
About the size of a lentil
What can be seen on the ultrasound?
Inside a gestational sac of about 13 mm, a 2–4 mm embryo can be seen right next to the yolk sac. The flickering in the middle of the embryo is the heartbeat; its rate is about 100–120 beats per minute and will increase over the coming weeks.
Your baby’s development
The embryo is about the size of a lentil. The neural tube closes and the brain develops rapidly. The first buds of the face and arms begin to appear.
Changes in your body
Nausea and vomiting may become more noticeable. Tiredness, breast tenderness and mood changes are common.
Check-ups at this stage
- First pregnancy appointment and transvaginal ultrasound
- Blood group and Rh factor, full blood count, thyroid (TSH), fasting blood sugar
- Tests for hepatitis B, HIV, syphilis and rubella immunity (as advised by your doctor)
Tips for this week
- Ginger, plain crackers and cold foods may help with nausea
- Only take vitamins and medicines after checking with your doctor
- Keep a pregnancy folder for your appointments and test results
When should you see your doctor?
Contact your doctor if you are vomiting so often that you cannot keep any fluids down during the day, pass noticeably less urine, or have heavy bleeding 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
What if no heartbeat is seen at 6 weeks?
If the embryo is very small, or your pregnancy is a few days behind the calculated date, the heartbeat may not be visible yet. In this case, a follow-up scan is done 7–10 days later.
When does nausea go away?
Nausea usually peaks around weeks 8–10 and eases considerably for many people by weeks 12–14.
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