There are three stages of pregnancy. These are the first, second
and third trimesters. The first trimester runs from week one to
week fourteen, the second covers weeks 15 – 26, then the third
is weeks 27 – 40.
Week 1+2: This is actually before you get pregnant. It’s the
stage where your body prepares itself by ovulating. And it’s in
these 14 days that the egg is fertilized by the sperm
Week 3: The fertilized egg now moves down the fallopian tubes,
fluid passes into the ball of cells, dividing them into two. The
inner cells will form your baby and the outer cells will form
the placenta. Your body, at this stage, is still unaware that it
is pregnant. The implantation begins as the cell ball reaches
the wall of the uterus. In this process the cells actually bury
into the uterus wall, which can sometimes lead to you having
spotting. The implanted cell ball now becomes an embryo.
Week 4: This is a week of rapid development, and your body now
realises it is pregnant. The amniotic sac and cavity begin to
develop and also the Yoke sac appears (this will later form the
baby’s digestive system). The placenta now starts to form where
implantation took place and blood from you will now go into the
placenta. It is usually about day 27 that we start to feel the
morning sickness.
Week 5: The primitive streak (the fore runner of the brain and
spinal cord) is now developing. Through this primitive streak
the cells will develop into three layers:
The endoderm: the bottom layer – develops the glands, lung
linings, tongue, bladder, digestive tract, tonsils, urethra and
associated glands.
The mesoderm: the middle layer – forms the muscles, bones,
heart, lungs, spleen, blood cells, and the reproductive and
excretory systems.
The ectoderm: the top layer – forming the skin, nails, hair, eye
lens, nose, mouth, anus, tooth enamel, pituitary gland, mammary
glands, and all parts of the nervous system.
Other cells will be starting to develop the spine (called the
notochord). The first steps towards forming the embryos head,
and the first formation of the babies blood cells happen this
week.
Week 6: The first few days of this week is when your baby’s
heart starts beating. The aorta (the largest artery in the whole
body) will be starting to form at around day 40. By mid week
many organs are starting to form: eyes, arm buds, liver, gall
bladder, stomach and intestines, lungs and pancreas.
Week 7: This is a busy week for your growing baby. During this
week your baby will double in size. The lenses of the eyes are
developing and there is also a recognisable tongue. The legs and
arms are developing into paddles, the jaws are now visible.
Week 8: The cerebellum starts to form this week. That’s the part
of the brain responsible for the movement of muscles. Also hand
and foot plates, elbow and wrist areas are forming. Towards the
end of the eight week the hand plate has formed ridges where the
fingers will be. There is further development of the eye;
pigment is now appearing on the retina. Teeth buds are now
forming within the gums, along with the wind pipe, bronchi, and
voice box. The heart is now starting to develop the four
chambers.
Week 9: Your baby is now starting to form cartilage and bones.
During this week the ovaries will develop into the sex organ
determining whether you’re having a boy or a girl. The fingers
and thumbs are now taking shape. Also the baby is now becoming
more active.
Week 10: It’s now that your embryo has become a baby, all be it
on a rather small scale. There is a fully formed upper lip. The
development of the heart now slows as it is past the critical
stage. By mid week the earlobes are fully formed. Toes start to
develop on the foot plate. As the bones of the palate (roof of
the mouth) start to fuse together, the tongue starts to develop
taste buds.
Week 11: as the morning sickness starts to subside, you may feel
your appetite increase. Your baby’s body starts to straighten.
In males the penis is now distinguishable and in females the
vagina is beginning to develop. This stage is where the baby
starts to show individuality, as the muscle structure varies in
each baby.
Week 12: Your baby will start to develop fingernails over the
next three weeks. The brain is now the same structure as it will
be at birth. By the end of the week, the gall bladder and
pancreas will be fully developed. Also the baby will now be
opening and closing its mouth.
Week 13: This week vocal chords will form in the larynx. Also
the intestines will move from the umbilical cord into the
abdomen, and will start to form folds and become lined with
villi.
Week 14: You may have noticed some changes to the areola (the
area around your nipple); it may be getting larger and darker.
Your baby’s heart beat will now be able to be heard using a
Doppler. Breathing, sucking and swallowing motions will be being
practised. The breathing practises will take the amniotic fluid
in and out of the lungs. Baby’s hand also becomes more
functional.
Week 15: The baby’s neck is now defined, with the head now
resting on the neck rather than the shoulders. The hair pattern
of the baby will be defined by the 102nd day of the pregnancy
your baby will now be able to turn its head, open its mouth,
kick, press its lips together and turn its feet.
Week 16: This week the baby’s toe nails will start to grow. The
muscles will be growing stronger and the neck and head are
growing straighter. As the uterus starts moving upwards you may
start showing more, but this does mean less pressure on your
bladder, making you feel like urinating less.
Week 17: Your baby will be working on more reflexes this week;
blinking, sucking, and swallowing. Development is carrying on
with all the existing structures. Through the course of this
month your baby’s weight will increase 6 times.
Week 18: By mid week your baby’s eyes and ears will now be in
the right places. The finger tips and toes will develop pads,
and toe and finger prints will start to develop later in the
week. Myelinization, a process of coating the nerves with a
fatty substance called myelin which speeds up nerve cell
transmission and insulates nerves, will start happening this
week. Also by the second day of this week meconium (faecal
waste) will start developing in the baby’s bowels.
Week 19: A creamy looking substance that covers the baby’s body,
vernix coseosa, will start to form. This protects the baby and
its developing glands and sensory cells. If you’re having a baby
girl primitive egg cells are now developed in the ovaries, in
fact females are born with all the eggs their ovaries will ever
have.
Week 20: Most of the major development has now taken place, and
the danger zone of the first three months is now over. Your baby
will be waking and sleeping, just as newborns do. Also the
formation of fine scalp hair and eyebrows will begin.
Week 21: Your body is replacing the amniotic fluid very three
hours at this stage of your pregnancy. Baby’s leg and arm
movements increase as the muscles and bones become stronger. By
the end of the week a stethoscope will be able to detect the
baby’s heart beat.
Week 22: If the baby is a boy, the testes will start to move
from the pelvic area into the scrotum. The hair on the head and
eyebrows is now visible as white and short.
Week 23: The bones in the middle ear start hardening making the
conduction of sound possible. The baby will start to gain some
considerable weight between now and next month. The size of the
baby’s body will start to get into proportion though the head
will remain larger than the rest of the body.
Week 24: The skin of your baby is wrinkled, but will smooth out
as fat is deposited. Also by the end of this week the baby’s
heart beat is so strong it is some times possible to hear it by
placing an ear on your stomach.
Week 25: Baby’s skin is now turning a reddish/pink as
capillaries start to develop. The nostrils will now start to
open, as they have been plugged unto now. The lungs will start
developing blood vessels and the finger and toe nails will now
be covering half the nail bed.
Week 26: with the nostrils now open, muscular breathing will
start. By the end of the week the lungs will be secreting
surfactant, a substance which prevents the lung tissue sticking
together. Also with the formation of blood vessels in the lungs,
they will now also be developing air sacks. Brain wave activity
starts this week for auditory and visual activity.
Week 27: Bumping and thumping is becoming stronger as your baby
grows stronger, you should be feeling around 10 kicks in a two
hour period. Baby’s lungs are growing rapidly and there is
continual development with brain patterns.
Week 28: This is when the eyelids un-fuse and open up. Muscle
tone is improving, and the lungs are capable of breathing air.
The chances of a baby being born premature from now on, has a
greatly improved chance of surviving.
Week 29: Eye lashes have now grown, and although still unable to
focus, baby’s eyes are now sensitive to dark and light. At this
stage of pregnancy the senses of sound, smell and taste are
developing. By the end of the week your baby will be able to
move its eyes in their sockets.
Week 30: Baby is now storing up nutrients taken in by you.
Calcium for skeletal development, protein for growth and iron
for blood cells. By the end of the week the languno (the small
hairs that covered the baby’s body), is nearly all gone apart
from some patches on the shoulders and back.
Week 31: As the actual growth starts to slow down, the internal
organs are still maturing, so make sure your still getting
enough folic acid, iron and calcium. Should your baby be born
this week they would have the ability to breath, see, listen
learn and remember.
Week 32: The baby’s iris is now reacting to light. All five
senses are now registering with your baby, although smell is
limited as baby can’t breathe air in the uterus.
Week 33: your baby may now be sucking its fingers. Constipation
could be starting for you as your uterus puts more and more
pressure on your bowels.
Week 34: The pigment of the eyes is not quite fully developed
yet, this leaves the eyes looking blue regardless of final
colour. And this week your baby will start to develop its own
immune system.
Week 35: In baby boys the decent of the testes will complete any
time now. Your baby may now shift into your pelvis in a head
down position, but not all babies’ do this before birth.
Week 36: Dimples on the elbows and knees will be forming as well
as creases in the neck area due to continual deposits of fat.
Also this fat will help baby maintain its body temperature.
Week 37: Around 85% are born within two weeks of their actual
due date (either before or after), so as you enter this stage be
aware for signs of labour. The baby is practising being more
aware of its surroundings; this is the ‘orientating response’.
This is where the baby will turn towards any source of light.
The end of this week marks the end of development, growth will
now slow down.
Week 38: Meconium is accumulating in the intestines. Meconium is
a dark green mass of waste product and cells from the gall
bladder, liver and pancreas. Although shortly after birth this
will all come out.
Week 39: as the baby is settling into your pelvis, you maybe
feeling clumsy and off balance. This is because your centre of
gravity shifts. Make sure you’re prepared for your trip to the
hospital.
Week 40: welcome to the final week, that’s if you have not given
birth already. Your body will be giving the baby antibodies so
it can protect its self from many diseases. The baby will finish
dropping into its resting place before birth. So congratulations
and welcome to your new born child.