PREGNANCY & FETAL

DEVELOPMENT

Sperm are made in the testes.

Tail helps the sperm to swim so it can find

the egg

Special chemicals at the tip help the sperm to get

into the egg

Very little cytoplasm so it can swim fast

Eggs are made in the ovaries.

Jelly coat means that only one sperm can

get into the egg.

Lots of cytoplasm so there is lots of food for the new baby.

It only takes one sperm to get into the egg to make a baby.

When a sperm joins with an egg, this is how

a new baby starts.

Stages of Reproduction

Fertilization~Joining of an egg and a sperm in the fallopian tube

Pregnancy – this is when a baby grows inside a woman.

The baby grows inside the womb (the uterus).

It is protected by a bag of water, and gets food

from the woman through the placenta.

Embryo:A fertilized egg in the first 2 months of pregnancy

Fetus:From the 3rd month on the embryo is called a fetus.

BABY DEVELOPMENT

(Adapted from Introduction to Biology, D.G.Makean; published by John Murray 1971)

(a)Eggs are produced in organ X. What is the name of organ X?(b) The baby grows in a bag of amniotic fluid which is inside organ Y. What is the name of organ Y?(c)Through which part, labeled in the diagram, is food passed from the mother to the baby?(d) Name one useful substance, other than food, which passes from the mother to the unborn baby.(e)The diagram shows an organ system of the mother’s body. What is the name of this organ system?

The Placenta Organ attached to the inside of the uterus

and connected to the fetus by the umbilical cord.

Produces pregnancy-related hormones “Trading-post” between mother and baby

(the baby gets oxygen and nutrients from the mother this way)

Mother/baby’s blood never mixes Pancake-shaped organ

The Umbilical Cord

A cord that attaches placenta to the fetus Can be 60 cm long Carries oxygen and nutrients from

placenta to fetus, carries fetus’s blood back to placenta

When this is cut, it forms your belly button!

The Amniotic Sac Sac containing the fetus Thin but tough pair of transparent

membranes Filled with amniotic fluid (at maximum, it

contains 1 L of fluid)

Amniotic Fluid

A protective liquid in the amniotic sac, surrounds fetus

Cushions fetus against blows to mother’s abdomen

Inhaled and exhaled by fetus Promotes fetal development Keeps a constant temperature

Fertilization

30 hours after fertilization

WEEK 3-5 The baby’s tiny heart begins to beat by day 21. The arms, legs eyes, lips

and nose begin to grow.

WEEK 7 The organs start to grow inside the

baby. The baby starts to move.

WEEK 8-12 The baby has hands and feet, and

swims and moves inside the bag of water.

FIRST TRIMESTER

Start of the 8th week Developing human is called a

fetus Brain waves can be detected Muscle movements begin Bones and muscles are developing All major body parts have formed

4th Week• Heart starts beating• Arm and leg buds appear• Eyes and brain begin to develop • Embryo is less than ¼ of an inch

long

Umbilical Cord Connects the embryo to the

placenta

First 3 Months

Weeks 13-20

The baby can swallow, and starts to try

breathing. It can feel pain, and moves

around a lot. It has eyebrows and

eyelashes now.

Week 20-24

The baby has hand and footprints. It practices

breathing.

Weeks 25 – 32

The baby’s eyes open and close, and it sleeps 90% of the time.

SECOND TRIMESTER

• Organ systems continue to develop

• By 4 months – mother can feel the fetus move or “kick”

• Reproductive organs can be recognized as distinctly male or female

• Fetus can hear and recognize voices

• Hair forms on the head

Months 4-6

Weeks 33 – 40

The baby is getting ready to be born. It turns upside down before it is born.

THIRD TRIMESTER

Months 7-9

•Time when the fetus gains most of its weight

•Most fetuses are about 20 inches

•Brain develops further

•All other organs are almost complete

•Fetus can grasp with his/her hands

•Fetus’s skin becomes smooth – fat deposits underneath the skin

•Nervous system will continue to develop after birth

Newborn baby

Stages of Birth:1.Labor – mild contractions pushes

the baby against the cervix

2. Birth – Baby pushes through the cervix

and into the birth canal.

3. After birth – After the baby is delivered, the placenta separates and is delivered.