Embryo Development (17-24 weeks)

1. Embryo Development
17th – 24th week

2. 17th week
• The skeleton is changing from soft cartilage
to bone, and the umbilical cord is growing
stronger and thicker.
• The sweat glands are starting to develop.
• Eyes start making small side-to-side
movements and can even perceive some
light, though the eyelids are still sealed.
• Myelin slowly begins to wrap around his
spinal cord. Sweat glands are start to
develop all over the baby’s body.

3. 17th week
• The retina has become sensitive to
light. The first stools (meconium) are
now beginning to accumulate.
• They recycle the amniotic fluid by
swallowing up to a litre a day. Fat
stores begin to develop under your
baby's skin this week. The fat will
provide energy and help keep your
baby warm after birth.
• Baby's eyes are looking forward now,
but they are still firmly closed.

4. 18th week
• Blood vessels are visible through thin skin, and
the ears are now in their final position.
• If it’s a girl, her uterus and fallopian tubes are
formed and in place. If it’s a boy, his genitals
are noticeable now. The girl will already be
developing eggs in her ovaries at 18 weeks.
• Tiny air sacs; alveoli begin to form in lungs and
the vocal chords are formed. Baby goes
through the motions of crying but without air
doesn't make a sound.

5. 18th week
• The skin is building a protective wax layer
(vernix).Vernix (a white cheese like protective
material) forms on baby's skin with the lanugo, a
soft lightly pigmented hair covering the body
and limbs, both help to protect the fetus skin
during the months in water.
• The fetus starts to yawn.
• Nerves, are forming more complex connections.
And those in the brain are further specializing
into the ones that serve the senses of touch, taste,
smell, sight and hearing.

6. 19th week
• In week nineteen kidneys are
making urine, and hair is
beginning to grow on the baby’s
scalp.
• The parts of the brain that are
responsible for the senses are
specializing .
• It can respond to light and start
thumb sucking, If it is a baby girl
she already has 6 million eggs
formed in her ovary.

7. 20th week
• The fetus starts to swallow more this week, good
practice for the digestive system.
• Week twenty the mother may begin to feel the
baby’s first movements known as quickening.
• This is normally when an ultra sound can detect
the sex of the baby.
• The baby can suck thumb, yawn, stretch and
make faces.
• Organs are getting into their proper places.
• Teeth are beginning to appear, and he can
swallow.

9. 21st week
• By 21st week of pregnancy, not only the
baby’s important systems develop, but many
of them now are operating, in preparation for
functioning on their own after birth.
• Taste buds could begin to form.
• Baby’s eyelids and eyebrows are fully
developed and now he can blink.

10. 21st week
• The baby’s digestive system is put to work.
• By 21st week of pregnancy, baby has probably
begin to swallow amniotic fluid.
• The fetus starts to absorb small amounts of sugar
from it.
• Baby’s bone marrow rather than baby’s liver and
spleen takes over its permanent job of making
blood cells.
• The arms and legs are in proportion by 21st week
of development.

11. 22nd week
• Baby gains about 3 ounces this
week. The weight is in muscle,
bone mass and organs. Taste buds
begin to form.
• The eyelids can be seen very
clearly.
• If born at this stage is officially
considered viable, they may well
be able to survive.

12. 22nd week
• The lungs are developing branches of the
respiratory tree and cells that produce
surfactant. This is a substance that helps the air
sacs inflate easily and also keeps the small air
sacs in our lungs from collapsing.
• Little creases have appeared on his palms. The
muscular coordination of the hands has
improved as they sucks their thumb. Over the
next week or so, the sweat glands will be
forming in the skin.

13. 23rd week
• Fully developed inner ear which
controls balance
• Skin pigment is now forming
• Pancreas (essential in the production
of hormones) is developing steadily
• Baby has begun producing insulin
(important for the breakdown of
sugars)

14. 24th week
• The baby practices breathing by inhaling
amniotic fluid into developing lungs
• The unborn baby is covered with a fine,
downy hair
• Skin is protected by waxy substance
• Unique hand and footprints are forming
• Some babies now kick in response to
sounds and touch from outside the womb