Pregnancy Week 8: Baby's Major Organs Are Forming

8 min read

Quick answer: At 8 weeks your baby is about 16mm from crown to rump, roughly the size of a kidney bean, and all the major organs — heart, brain, lungs, liver, kidneys and intestines — are forming. The heart beats around 150 to 170 times a minute. Book your NHS booking appointment before 10 weeks if you haven't already.

What parents need to know

Welcome to week 8 of your pregnancy. You may still be in the thick of first trimester symptoms (nausea, fatigue, sore breasts), but this week marks progress for your growing baby. All of the major organs are now forming, and your baby is beginning to look unmistakably human.

Baby's size	About 16mm, roughly a kidney bean
Heart rate	Around 150 to 170 beats per minute
Your uterus	Roughly the size of a large lemon
Booking appointment	NHS recommends before 10 weeks
Combined test	Offered at your 12-week scan; your choice

How big is your baby at 8 weeks?

Your baby is now about the size of a kidney bean, roughly 16mm from crown to rump. Growth is happening fast. Your baby has almost doubled in size since last week.

What's happening with your baby?

This week is a period of extraordinary activity at a cellular level. All of your baby's major organs (the heart, brain, lungs, liver, kidneys, and intestines) are in the process of forming, even if they won't be fully functional for many weeks yet. Your baby's heart is beating rapidly at around 150 to 170 beats per minute, roughly twice the speed of an adult heart. The hands and feet are forming, and tiny webbed fingers and toes are starting to separate. Eyelids are forming over the eyes, and your baby's nose, lips, and jaw are becoming more distinct. A primitive version of the digestive system is developing, including the oesophagus and stomach.

Your baby is also beginning to move, though you won't feel any movement for several weeks yet. These early movements are reflex responses to the rapidly developing nervous system.

A touching moment of a baby gently holding a parent's finger, conveying warmth and connection.

What's happening in your body?

At 8 weeks, your uterus is roughly the size of a large lemon — you can't see it from the outside, but it is expanding steadily. Your body is working hard to build a rich blood supply for the placenta, which means your blood volume is increasing significantly. This can contribute to feelings of dizziness and lightheadedness.

Common symptoms at week 8 include continued nausea (which may be peaking around now), extreme tiredness, more frequent urination as your kidneys process an increased volume of blood, vivid or unusual dreams (a common but poorly understood side effect of pregnancy hormones), and heightened emotions. Constipation and bloating may also be bothersome. Some women notice their skin changing — some develop a pregnancy glow thanks to increased circulation, while others may experience spots or dryness.

Your antenatal appointments

If you haven't yet had your booking appointment, it should be happening very soon. The NHS recommends this takes place before 10 weeks so that all blood tests, screenings, and scan referrals can be arranged in good time. If you're still waiting to hear from a midwife, contact your GP surgery to chase the referral.

The NHS offers all pregnant women a screening blood test called the combined test, also known as the first trimester screening. This is carried out at your 12-week scan appointment and screens for the risk of chromosomal conditions such as Down's syndrome, Edwards' syndrome, and Patau's syndrome. You do not have to accept this screening — it is entirely your choice — but your midwife will give you information about it so you can make an informed decision.

Nutrition in the first trimester

Eating well during pregnancy is important, but with nausea often at its peak around week 8, this isn't always easy. Focus on what you can manage rather than what you think you should eat. If your diet has been limited due to sickness, try to incorporate nutritious foods when you feel able: wholegrain carbohydrates for slow-release energy, lean protein such as eggs, pulses, or fish, dairy or calcium-rich alternatives, and plenty of fruit and vegetables where tolerable.

Foods to avoid during pregnancy include raw or undercooked meat, game meats such as pheasant and venison, raw fish and raw shellfish, unpasteurised milk, cream, yoghurt, butter and ice cream, and shark, swordfish and marlin. Hen eggs without the red British Lion stamp or the Laid in Britain logo, and duck, goose and quail eggs, should only be eaten well cooked. Some foods are only safe if cooked until steaming hot: soft mould-ripened cheeses such as brie and camembert and soft blue cheeses (even if they're pasteurised), other foods made from unpasteurised milk, cold-smoked or cured fish such as smoked salmon, cold pre-cooked prawns, and cold cured meats such as salami. Limit oily fish to 2 portions a week and tuna to 4 cans or 2 tuna steaks a week. Liver and liver products should also be avoided as they contain very high levels of vitamin A, which can be harmful to a developing baby. For the same reason, do not take cod liver oil or supplements containing vitamin A (sometimes called retinol). Always check the label.

When to get help

Some symptoms in pregnancy can be a sign of something serious and need checking quickly. This is who to contact, and how soon.

Call 999 if:

you're bleeding from your vagina and the bleeding is heavy (soaking a period pad soon after putting it on), or you also have severe pain in your tummy, pain in your shoulder, or feel sick, faint, dizzy or lose consciousness
you have a sharp, sudden and intense pain in your tummy together with feeling very dizzy or fainting, feeling sick or looking very pale, as this could mean an ectopic pregnancy has ruptured (you can also go straight to A&E)
you have severe difficulty breathing (you're gasping, choking or not able to get words out) or your chest feels tight or heavy
you have pain and swelling in one leg and you also feel short of breath or have chest pain. A blood clot in the leg can travel to your lungs, which can be life-threatening
you have possible signs of sepsis, such as breathing very fast, being confused or having slurred speech, blue, pale or blotchy skin, a rash that does not fade when you press it, or a very high or very low temperature. Being pregnant makes sepsis more likely
you do not feel you can keep yourself safe (a mental health emergency is as serious as a physical one)

Always call 999 if you think it's a life-threatening emergency, no matter what stage of pregnancy you are.

Contact your GP or early pregnancy unit right away if:

you have light bleeding or spotting, even if you have no pain or only mild tummy pain
you have vaginal discharge that's unusual for you, or fluid leaking from your vagina
you have tummy pain low down on one side, or pain in the tip of your shoulder (where your shoulder ends and your arm begins). Symptoms of an ectopic pregnancy usually start between 4 and 12 weeks, so get advice right away, even if you have not had a positive pregnancy test yet
you have stomach pain that is severe or does not go away after you've rested for 30 to 60 minutes, or stomach pain with regular cramping or tightenings, lower back pain, or pain when you pee
your breathlessness comes on suddenly, you're out of breath when you're lying down, or you're breathless and also have chest pain or feel dizzy
you have pain or swelling in one leg, usually in the calf or thigh. This could be a blood clot (deep vein thrombosis, or DVT), which is more likely when you're pregnant
you have a high temperature (38C or above), or you feel hotter than usual or shivery. A high temperature can be a sign of an infection, so it's important to get it checked

If you cannot reach them, or you're not sure what to do, call NHS 111.

Speak to your GP or midwife if:

you're worried about your mental health, or stress, anxiety or low mood are affecting your day-to-day life. If you need urgent help for your mental health, call 111 and select the mental health option, or ask for an urgent GP appointment

Your week 8 checklist

This week:

This week

Attend or confirm your booking appointment.
Take folic acid and vitamin D daily.
Eat what you can manage and try to stay hydrated.
Review the NHS guidance on foods to avoid in pregnancy.
Rest when you need to.
Check in with your mental health. It's just as important as your physical wellbeing.

Sources: NHS, Tommy's, NCT. General information, not medical advice.

Sources & further reading

General information, not individual medical advice. Speak to your GP, midwife or health visitor about your baby’s needs.