Pregnancy Week By Week
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.
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Keywords: amniotic sac, blood cells, bottom layer, digestive system, digestive tract, excretory systems, eye lens, fallopian tubes, first trimester, glands, implantation, morning sickness, parts of the nervous system, pituitary gland, primitive streak, rapid development, stages of pregnancy, tooth enamel, trimesters, urethra.
