6 weeks pregnant: morning sickness and seeing a heartbeat
6 weeks pregnant is a stage at which, the NHS says, the embryo is around 6 mm long and its arms and legs are starting to form as limb buds (NHS, 2026). This page sets out what the NHS, ACOG and NICE say about week 6.
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Medically reviewed by Dr Mary Davidson, Reproductive endocrinologist, checked on
Seek help now if you have any of these symptoms
Bleeding and cramping are common in early pregnancy and often do not mean miscarriage. The symptoms below, however, need to be assessed straight away.
- Soaking two or more sanitary pads per hour, or passing large clots
- Severe lower abdominal pain, especially on one side
- Pain at the tip of the shoulder
- Dizziness, fainting, or collapse
- Signs of shock — pale, clammy, rapid heartbeat, breathlessness
- Pain on opening bowels, or bladder or bowel changes
- Feeling very unwell, or feverish
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How the sources describe development around 6 weeks
- Size and shape, NHS
- The NHS week 6 page in its week-by-week guide (NHS, 2026) gives the embryo as around 6 mm long. Its introduction compares the size to a baked bean and the section on the baby compares the size and shape to a pea, so the page uses two comparisons. It says some people think the embryo resembles a tadpole with its little tail.
- Development, NHS
- The NHS says the arms and legs are starting to form as limb buds, there are tiny dents where the ears will be, a bump where the heart is and another bulge where the head will be, and that the embryo is covered with a thin layer of transparent skin. It says the liver, brain and musculoskeletal system are also developing (NHS, 2026).
- Development, ACOG
- ACOG’s list for weeks 1 to 8 includes the lungs starting to form the tubes that will carry air in and out after birth, and the inner ear beginning to develop. It does not date these to a single week (ACOG, How Your Fetus Grows During Pregnancy, 2024).
Weeks are counted from the first day of the last menstrual period, so about two weeks of the count come before conception (ACOG, How Your Fetus Grows During Pregnancy, 2024). This page covers 6 weeks 0 days to 6 weeks 6 days.
A normal pregnancy lasts about 40 weeks from the first day of the last menstrual period, so at 6 weeks about 34 weeks remain to the estimated due date (ACOG, How Your Fetus Grows During Pregnancy, 2024). Your own due date depends on your last period or a scan, not on the week alone.
Nausea, as the NHS describes it
The NHS says morning sickness can occur at any time of day, although it is usually worse when you first wake up. It lists things some people find helpful, including small meals, rest, ginger, sucking ice cubes and travel acupressure wristbands, and it says that if you cannot keep food down you should talk to your midwife or doctor (NHS, 2026). When does morning sickness start sets out when nausea usually begins, peaks and ends, and hyperemesis gravidarum covers sickness that is severe.
The NHS also says that a lot of people start to feel better after the first trimester, and it asks anyone worried about a symptom to talk to their midwife or doctor (NHS, 2026).
Hearing the heartbeat
The NHS says that sometimes the heartbeat can be picked up by a vaginal ultrasound scan, but that you are unlikely to be offered one unless you have had IVF (NHS, 2026). Scan timing in routine NHS care is different: NICE guideline NG201 recommends a scan between 11 weeks 2 days and 14 weeks 1 day (NICE, 2021).
Symptoms the NHS lists
At 6 weeks the NHS lists morning sickness and tiredness along with a metallic taste in the mouth, sore breasts, mood swings, headaches, food likes and dislikes, a heightened sense of smell and light spotting, and it repeats that you should see your doctor if you get bleeding in pregnancy (NHS, 2026). Spotting during pregnancy covers what the NHS says about spotting.
Work out which week you are in
The Pregnancy week calculator takes your last period, conception date, scan or IVF transfer and shows how many weeks and days pregnant you are today.
Sources
- NHS Best Start in Life. Week 6 of pregnancy (week-by-week guide to pregnancy). nhs.uk, 2026.
- American College of Obstetricians and Gynecologists. How Your Fetus Grows During Pregnancy (FAQ156). ACOG, 2024.
- National Institute for Health and Care Excellence. Antenatal care (NG201). NICE, 2021.
Frequently asked questions
How big is the baby at 6 weeks pregnant?
The NHS says the embryo is around 6 mm long, and compares it to a pea in one place and a baked bean in another (NHS, 2026). It does not give a weight.
Can a heartbeat be seen at 6 weeks?
The NHS says a vaginal ultrasound scan can sometimes pick up the heartbeat, but that you are unlikely to be offered one at this stage unless you have had IVF (NHS, 2026).