Pregnancy Week 8: Baby's Major Organs Are Forming

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 incredible progress for your growing baby. All of the major organs are now forming, and your baby is beginning to look unmistakably human.

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.

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, shellfish, soft cheeses made from unpasteurised milk, pâté, raw eggs, shark, swordfish, and marlin (due to high mercury levels), and large amounts of oily fish (limit to two portions per 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.

Your week 8 checklist

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 is just as important as your physical wellbeing.