The Complete Guide to Pregnancy Week by Week

Posted on Sep 19 2015 - 7:07am by admin

Pregnancy is a complicated process and the effects on your body as a woman are quite drastic as the weeks progress.

Once an egg is fertilized and implants itself in the uterus, conception has officially happened, and the pregnancy journey starts.

Here is a brief outline of the main stages during the full 40 weeks of pregnancy, from the start of pregnancy till you gift birth.

Week 4

The pregnancy is growing rapidly.  By the 28th day it is just visible to the naked eye.  Because growth is so rapid from now to the end of the 12th or 13th week, the developing baby is particularly vulnerable to damage from things such as drug use or rubella.  Any severe infection that the mother suffers during this time could also be a risk to the baby so it is a good idea to seek medical help early for any infectious illness.

Week 5

The developing baby is now about 0.07 inches long and lying in the amniotic sac which is full of shock-absorbing fluid to protect the baby.  The spine can be seen and the beginning of the nervous system is developing.

Week 6

The head is now rapidly forming and then the chest and abdominal cavities.  The young brain is completed although considerable growth is still needed.  The spinal cord and spinal column is properly formed.  Limb buds become more visible, and the umbilical cord is becoming more obvious.  The baby is about 0.24 inches long and early facial feature development can be seen by shadows on the surface.

Week 7

By the end of this week the limb buds have grown so rapidly that they are clearly seen as arms and legs, and at the ends little indentations that will become fingers or toes are visible.  The baby now has its own blood vessels and circulation system.  And at this point, a basic version of the heart is operating to move the blood around the body.  The lungs are there, but are tiny and solid at this stage, and liver and kidneys are developing.  The head is developing rapidly and ears and eyes are forming.  The baby is now approximately 0.5 inches long.

Week 8

All the important organs are now developing and will continue to grow.  The heart is beating strongly and lungs are growing.  During this week, the eyes and ears do most of their growing.   The genitals can be seen.  Nostrils and upper and lower jaws develop so the mouth is forming.  The growing limbs have developed shoulders, elbows, hips and knees.  The spine begins to move, even though the baby is only 0.8 inches long.

Week 9

The head is still bent forward onto the chest but the baby looks much more like a baby.  The eyelids are still intact over the eyes but they have completely grown.  There is now a nose, and the mouth is growing rapidly.  Hands and feet have developed and fingers and toes are growing.  There are more definite movements, although most likely the mother will not feel them yet.  The baby is now about 1.2 inches long and weighs about 0.07 ounces.

Week 10

Although you are not obviously pregnant – no baby bump yet – the baby is now about 1.8 inches long and weighs about 0.18 ounces.  The baby looks far more human than even a couple of weeks’ ago.  The ankles and wrists have formed and fingers and toes are obvious, although connected by webbing at this stage.  The placenta is not yet completed formed but is developing rapidly.

Week 11

The baby is now about as long as mom’s little finger – 2.2 inches and weighing about 0.35 ounces.  At this stage all the essential organs have been formed and most are beginning to do the work they will do for a lifetime.  External genitalia are developing rapidly.  The facial features are clarifying, spine and limbs are moving.  The danger period for a developing baby is almost at an end.

Week 12

Your uterus has begun to expand outside the protective pelvic bones. It will increase in size by almost 1,000 times by the end of your pregnancy! You may really be starting to show now, especially if it’s not your first baby.

Week 13

You are now officially three month’s pregnant and the risk of miscarriage is diminishing.  The mother’s stomach may be swelling slightly.  The baby’s head is now quite round and the neck is formed so the head can move easily.    Mouth, nose, outer ear and eyes are properly developed.  Some mothers may feel movement around this stage, but for others it may take longer.  The baby is just 3 inches long and weighs just over an ounce.  By the end of the 13th week the baby is fully formed, from here onwards the baby will grow and organs will mature and “learn” their jobs until it is time for the baby to be born.

Week 14

Morning sickness should (hopefully!) start to ease by now, and you may have renewed energy levels.  But don’t overdo it!

Week 15

This is a good stage to discuss any diagnostic pre-screening with your health professional.

Week 16

The hair starts to appear, first as a downy layer over the whole body, then also on the head, eyebrows and eyelashes.  The baby is now nearly 6 inches long and nearly 5 ounces.

Week 17

This would be a good time to book in for childbirth education classes.

Week 18

Teeth may start to form, and the baby may react to noises.

Week 19

Your baby might start sucking their thumb around this stage.

Week 20

The baby has now grown considerably and is now around 10 inches and weighing 12 ounces.  There is a lot of fluid around the baby in which it can float and move, and it does!  Some babies are more active than others, and you will soon know.  Around 18 – 20 weeks into the pregnancy you should be able to have an ultrasound to determine the gender of your baby if you want to know.

Week 21

If you’re 35 or older, have chronic high blood pressure or diabetes or are carrying multiples, you are at a higher risk of preeclampsia. It can occur this early, but usually doesn’t set in until the third trimester.  If you have any signs of preeclampsia, eg swelling, weight gain, headaches, nausea or vomiting.

Week 22

You may develop constipation or haemorrhoids, so keep up with the fluids and fibre!

Week 23

This might be a good time to plan that final trip away to relax before the baby arrives.

Week 24

The vital organs are now mature enough for the baby to actually survive for a short time if it were born at this stage.  However any baby born at this stage would require significant medical support and intervention to survive.

Week 25

Leg cramps and heartburn may become a problem – stock up on indigestion tablets.

Week 26

The baby will be sleeping for longer periods now, often at the same time you do.

Week 27

You may notice increasing weight gain from here on.

Week 28

The baby will be opening and closing their eyes, and the eyes will develop the colour pigment for their eventual eye colour.

Week 29

The baby is increasingly sensitive to light and sound.  You may start to experience Braxton Hicks (“practice”) contractions anytime from now on.

Week 30

As the baby grows, your uterus will press onto your diaphragm, which may leave you feeling more breathless.

Week 31

By this stage, pressure on your bladder will mean multiple trips to the bathroom night and day!

Week 32

The baby is now perfectly formed with its head in proportion to its body.  The baby can now open its eyes and wriggles and kicks vigorously.    The average baby at this stage is 16 inches long and weighs around 3.5 pounds.  It usually lies with its head downwards, towards the pelvis, although it moves a lot and it may change position from time to time.

Week 33

This would be a good time to finalise your delivery plan, and perhaps attend a breastfeeding class if you are planning to breastfeed.

Week 34

The baby’s eyes will open when awake and close when they’re asleep, and will also react to light.

Week 35

Nervous system and immune system are still maturing, but the baby is well developed.

Week 36

The only part of the body not fully matured at this stage is the lungs.  There is now less room for the baby to move, so the level of discomfort for you will increase as the kicks hit stomach or ribs!  The baby’s head may now move down into the pelvis – said to be “engaged” – and once this happens the kicks may not hit the stomach and ribs so much.  The baby is now around 18 inches long and about 5.5 pounds.

Week 37

Your breasts may be leaking colostrum (baby’s first food), so it is a good time to buy some nursing pads to have in supply.

Week 38

It would be advisable to pack your bag for the hospital about now, in case you go into labor early.  In general, once your water breaks, or if contractions are 5 – 10 minutes apart – it’s time to head to the hospital.

Week 39

Get as much sleep as possible!   At week 39, your baby is fully developed and anywhere from 17-23 inches long and weighs 6-10 pounds.

Week 40

This should be the last week of pregnancy – in theory!  Many people go over this timeframe, especially with first babies.   The size of the baby and its maturity may have an effect on how long the pregnancy lasts.  For example a woman carrying twins will very often go into premature labor, before the 40 weeks are up, because the combined weights of the babies triggers her body into starting labor.

At full term, the baby is not only fully developed but has a considerable amount of fat padding.  The baby may be completely bald or may have hair up to 1 – 2 inches long.   Finger and toe nails are developed.

The next step is for labour to start and to deliver the baby.