10 Weeks Pregnant: Baby Development

Ten weeks is a landmark moment in early pregnancy. Your baby has officially completed the embryonic period and is now technically a foetus — a word that simply means the developmental stage during which all the major organs are formed and begin to function. From this point on, growth and refinement are the main story. Here is what is happening at ten weeks.

Baby Size at 10 Weeks
From Embryo to Foetus
Development Milestones
Bones, Muscles and Movement
Organ Development
Placenta Development
What You Might Be Feeling
Frequently Asked Questions

Baby Size at 10 Weeks

Your baby is now approximately the size of a strawberry — around 3 to 3.5 cm from crown to rump. This may still sound small, but it represents roughly a doubling in size over the last two weeks. The head remains proportionally large compared to the body, accounting for roughly half of the overall length, which is entirely normal at this stage of development.

From Embryo to Foetus

The transition from embryo to foetus at around week ten is not just a change in terminology — it marks a genuine shift in developmental focus. During the embryonic period (weeks four to nine), all of your baby's major organs and structures were formed from scratch. By week ten, that foundational work is essentially complete. The foetal period that follows is about growth, maturation, and refinement rather than the creation of entirely new structures.

This is why the risk of certain developmental problems related to organ formation decreases significantly after the first trimester. The critical window for many structural developments has passed by the time you reach ten weeks.

Development Milestones

At ten weeks, several notable developments are visible or underway:

Fingers and toes are now fully separated. The webbing that was present between the digits in earlier weeks has broken down, leaving individual fingers and toes clearly defined.
Facial features are becoming more refined. The eyes have moved closer together on the front of the face (rather than the sides), the nose is taking shape, and the upper lip is fully formed.
External ears are forming, positioned low on the sides of the head — they will migrate upward to their final position over the coming weeks.
The tail — the small tail-like structure visible in earlier weeks — has now disappeared completely.
Vital organs including the liver, kidneys, intestines, brain, and lungs are all present and beginning to function, though they will continue maturing throughout pregnancy.
Tiny fingernails are beginning to grow from the nail beds that formed in earlier weeks.
The genitals are beginning to differentiate internally, though it is still too early for external sex characteristics to be visible on a scan.

Bones, Muscles and Movement

One of the key changes at ten weeks is the beginning of bone hardening, a process called ossification. Until now, your baby's skeleton has been largely made of soft cartilage. At ten weeks, calcium starts being deposited into the cartilage framework, gradually converting it into harder bone. This process continues throughout pregnancy and beyond — some bones don't fully harden until young adulthood.

Alongside bone development, your baby's muscles are becoming stronger and better coordinated. Your baby is already making spontaneous movements — small kicks, stretches, and flexing of the limbs. You will not be able to feel these movements yet; that typically begins between 16 and 25 weeks for most people. But the movements are real and can sometimes be seen on ultrasound at this stage.

These early movements are not yet purposeful or conscious — they are the result of developing nerves and muscles firing. However, they are an important part of development: movement helps muscle fibres form correctly and supports healthy joint development.

Organ Development

The major organs are all present and operational in a basic sense by week ten, though each will continue to mature:

Heart: beating strongly at around 160 to 180 beats per minute — much faster than an adult heart. All four chambers are present and functioning.
Brain: growing rapidly, with the two cerebral hemispheres beginning to take shape.
Intestines: initially developing outside the body in the umbilical cord before returning to the abdominal cavity — a normal part of development that resolves by around twelve weeks.
Kidneys: beginning to produce small amounts of urine, which becomes part of the amniotic fluid.
Liver: taking over from the yolk sac as the main site of blood cell production.
Stomach: beginning to produce digestive juices, though there is nothing to digest at this stage.

Placenta Development

By ten weeks, the placenta is well established and rapidly maturing. It is taking over from the yolk sac as the primary source of nutrition and oxygen for your baby. The placenta also produces progesterone at increasing levels, which helps maintain the pregnancy and is responsible for some of the symptoms you may still be experiencing, including fatigue, bloating, and emotional sensitivity.

The placenta will continue growing throughout pregnancy, eventually weighing around 500 to 600 grams at term. Its health and positioning are assessed at your dating scan and again at your 20-week anomaly scan.

What You Might Be Feeling

For many people, week ten is deep in the most demanding part of the first trimester. Nausea and fatigue often peak around weeks eight to ten before gradually beginning to ease in the second trimester. You may also notice:

Increased or decreased appetite depending on nausea levels
Bloating and constipation as pregnancy hormones slow digestion
Visible veins on your breasts or abdomen as blood volume increases
Emotional sensitivity and mood fluctuations
Occasional headaches
Continued breast tenderness

If nausea is severe and you are unable to keep fluids down, contact your GP or midwife. Hyperemesis gravidarum (severe pregnancy sickness) is a medical condition that can require treatment, and you should not feel you have to manage it alone. Treatment options including anti-sickness medication are safe in pregnancy and can make a significant difference to your quality of life.

Your dating scan — the first routine NHS ultrasound — is likely coming up soon if you haven't had it already. This scan is usually offered between 8 and 14 weeks, most commonly around 11 to 13+6 weeks. It will confirm your gestational age and estimated due date, check for a heartbeat and visible anatomy, and screen for chromosomal conditions using the nuchal translucency measurement.

Frequently Asked Questions

### How big is my baby at 10 weeks?

Your baby is approximately the size of a strawberry, around 3 to 3.5 cm from crown to rump. The head still accounts for a large proportion of that length, which is normal. Growth continues rapidly throughout the first trimester.

Can I see my baby moving on a scan at 10 weeks?

Yes — if you have a scan at ten weeks you may be able to see your baby making spontaneous movements such as small wriggles, limb movements, or even what looks like a somersault. These movements are produced by the developing muscles and nervous system. You won't feel them yourself until later in pregnancy, but seeing them on screen can be very reassuring.

When will I start to show at 10 weeks?

Most people do not have a visible bump at ten weeks, though you may feel bloated or notice your clothes feeling tighter around the waist. The uterus is approximately the size of a large orange at this stage and is still largely within the pelvis. Visible bumps typically appear between 12 and 20 weeks, though this varies considerably depending on your build, whether this is your first pregnancy, and other individual factors.

Always speak to your midwife or GP for personalised advice about your pregnancy.