Month 1: Grow baby, grow!

Every week of your pregnancy comes with something to marvel at as you grow a whole human being from just two cells.

WEEK ONE

The fertilised egg becomes a ball of cells that floats into the uterus and implants in the lining. It divides into two sections. The outer layer develops into a protective cocoon around the embryo.

WEEK TWO

The embryo burrows into the uterine lining and grows finger-like projections that absorb nutrients from your blood.

WEEK THREE

The embryo is a tiny disc that folds over itself to form a tube. This is the beginning of the neural tube, the foundation of the brain and nervous system. The primitive heart is already beating and the baby’s blood is now pumped around his body. The folds that grow forward to become the face start to join in the front.

WEEK FOUR 0.4g

The eyes, nose and mouth become identifiable. There are spots where the eyes and ears are beginning to form and tiny bumps where the arms and legs will appear.

WEEK FIVE

Arms and legs get longer and acquire slight bends. Tiny paddles spread at the ends where hands and feet will develop. Cartilage forms from tissue for the fingers and toes. The roof palate of the mouth is forming. Blood vessels connect the foetus to the placenta via the umbilical cord.

WEEK SIX 1cm

Blocks of the tissue that will become the vertebrae are forming. The embryo has gill-like structures that will become the jaw, neck and face. The rudimentary heart starts to bulge. Nerve channels and muscles have linked up, and the embryo starts to move. Bone condenses out of tissue and is laid down over the cartilage.

WEEK SEVEN 2cm

The liver starts to function and supplies the embryo’s blood cells that, until now, were supplied by the yolk sac. The cells between the ridges of the fingers and toes start to die off.

WEEK EIGHT 2g

The eyes, which are always open and set very wide apart, move forward on the face.

WEEK NINE 10g

The eyelids grow over the eyes, closing them until they open again in the sixth month.

WEEK 10 5cm

Hands and feet are well developed; fingernails and toenails start to grow.

WEEK 11

Amniotic fluid flows in and out of the lungs, and the diaphragm begins to move in preparation for breathing.

WEEK 12 19g, 8cm

Your baby inhales amniotic fluid into his lungs and starts “practice” breathing, even though oxygen reaches him through the umbilical cord. His digestive system processes the amniotic fluid, and some nutrients are extracted. A small amount of solid waste accumulates in his intestine. Taste buds are present on the tongue, and he can taste the amniotic fluid. Eyelids are formed but can’t open yet. Your baby is producing his own urine and is now fully formed. The framework for all the organs, limbs, muscles and bones is already in place. Your baby starts to hear.

WEEK 13 9cm

The fingers grow longer and more tapered, and fingernails continue to grow.

WEEK 14 45g

The skin is so transparent that it reveals the fine underlying blood vessels. Complex movements such as lip movements, sucking, and facial expressions such as frowning and grimacing are present.

WEEK 15

A fine hair called lanugo starts to grow on the eyebrows and upper lip.

WEEK 16 110g, 14cm

The organs start to round out the belly, but the limbs are lean and lanky.

WEEK 17 17cm

Your baby accumulates brown fat, which is rich in cell structures that turn fat directly into energy to keep him warm.

WEEK 18 200g

The nerves cells in the brain have reached the maximum number, and signals travel faster on their trips to and from the brain.

WEEK 19

A white, cheesy coating called vernix caseosa starts to appear on your baby’s body, making him waterproof.

WEEK 20 300g

Your baby begins to acquire a regular pattern of sleeping and waking.

WEEK 21 20cm

Weight gain speeds up.

WEEK 22 460g

Your baby looks old and wrinkled because he still doesn’t have much fat underneath his skin. He sleeps and wakes now, so you may notice periods of quietness and activity.

WEEK 23

Hair begins to grow, first on the eyebrows and eyelashes and then on the head. Limbs are well developed, and hands are able to grip. You will be able to identify different parts of your baby’s body through the abdominal wall.

WEEK 24 600g, 23cm

The foetal lungs have just begun making surfactant, a detergent-like substance that helps the lungs expand and take in air. The lungs start making breathing movements.

WEEK 25 24cm

The sense of hearing is developed, and the foetus is startled by loud noises. Waking and sleeping patterns are established.

WEEK 26 820g

The eyes open and your baby can now blink.

WEEK 27

Your baby’s lungs can expand, but he still breathes through the umbilical cord. The eyelids are open and eyelashes are present.

WEEK 28 1,1kg

Your baby lays down more fat, smoothing out and filling out his wrinkly skin. If you expose your pregnant belly to the sun, light filtering through the abdominal wall may be seen by baby as a reddish haze. Eyes develop the ability to focus.

WEEK 29 28cm

Many babies start to adopt an upside down position with their heads pushing into the pelvis. Nerve circuits in the cerebral cortex (for conscious thought and remembering) are already as advanced as those of a newborn. The fingernails are fully grown but toenails are not.

WEEK 30 1,3kg

The fine hair (lanugo) starts to disappear.

WEEK 31

Your baby is making breathing motions, narrowing his pupils, focusing and blinking. The skin is becoming pink rather than red as a result of the white fat deposits that have been laid down beneath it. These will provide energy and regulate temperature after your baby is born.

WEEK 32 1,8kg, 30cm

Your baby’s muscles are constantly contracting and relaxing, and her pupils respond to light.

WEEK 33 31cm

Your baby spends 80 percent of the time breathing amniotic fluid.

WEEK 34 2,1kg

Fluid passes through his kidneys and contributes to the amniotic fluid. The immune system is still immature, and your baby continues to receive your antibodies.

WEEK 35

Your baby looks pinkish and smooth now that a layer of fat has been deposited.

WEEK 36 2,2kg, 34cm

He is gaining about 14g of fat a day to cope with lower temperatures after birth. Meconium is being produced in the intestines.

WEEK 37 35cm

His face is filling out, she has eyelashes, and her eyelids open and close easily. Your baby will be practising breathing, sucking and swallowing.

WEEK 38 2,9kg

The lanugo and vernix have almost completely disappeared, although a few spots may remain on the back or in the folds of the skin.

WEEK 39

The shed lanugo is swallowed by the baby and accumulates in his bowel. This forms a green-black ooze called meconium.

WEEK 40 3,2kg, 51cm

His rate of growth slows down. At term, most babies weigh 3 to 3.6kg. ●