There are three stages of fetal development: germinal, embryonic and fetal.
Germinal Stage
Time Frame: Generally considered to start around the time of fertilization (week 2 of pregnancy)
Key Events:
Fertilization occurs around week 2, as the sperm meets the egg.
The zygote rapidly divides to form a blastocyst.
By the end of week 2, the blastocyst implants into the uterine lining.
Embryonic Stage
Time Frame: Weeks 3-8 of pregnancy
Key Events:
The blastocyst officially becomes an embryo around week 3.
Major organs and body structures begin to form.
By the end of week 8, all major organs have developed.
Fetal Stage
Time Frame: Week 9 until birth
Key Events:
The embryo is now referred to as a fetus, beginning around week 9.
Rapid growth and development of body systems continue.
By the end of pregnancy, the fetus is fully formed and ready for birth.
Beside these stages fetal development also categorized into three growth stages.
First Trimester (Weeks 1-12)
Weeks 1-4 (The Start):
At the very beginning, the baby starts as a tiny ball of cells called a blastocyst.
This little ball attaches itself to the lining of the uterus.
The brain, spinal cord, and heart begin to form.
This is when you might start to notice signs of pregnancy, like a missed period or morning sickness.
Weeks 5-8 (Tiny Features):
The embryo starts to grow arms, legs, eyes, and a beating heart.
By week 8, all the major organs have started to form.
It's still very small, about the size of a raspberry, but it's developing quickly.
Weeks 9-12 (Baby's First Movements):
The embryo is now called a fetus, which means "young one" in Latin.
It can move its arms and legs, although mom can't feel it yet.
Fingers and toes are developing, as well as tiny nails.
By the end of the first trimester, the fetus looks more like a tiny human, with facial features forming.
Second Trimester (Weeks 13-26)
Weeks 13-16 (Growth Spurt):
The fetus starts growing rapidly.
It might suck its thumb, yawn, or make other cute movements.
Bones start to harden, and tiny hairs called lanugo cover its body to keep it warm.
Weeks 17-20 (Hello, Kicks!):
Mom can usually feel the baby's first movements, called "quickening."
Eyebrows, eyelashes, and hair start to grow.
The fetus can hear sounds from outside the womb, like mom's voice.
Weeks 21-24 (Sense of Balance):
Taste buds are developing.
The fetus can now sense changes in its position and might even do somersaults!
Lungs are forming, but they're not ready to breathe air yet.
Third Trimester (Weeks 27-40)
Weeks 25-28 (Eyes Wide Open):
Eyes can open and close.
The fetus sleeps and wakes at regular intervals.
Lungs are still maturing, getting ready for that first breath.
Weeks 29-32 (Growing Rapidly):
The baby's bones are fully developed, but still soft and flexible.
It might hiccup, which feels like a little twitch in mom's belly.
Skin is smoothing out as fat deposits under the skin increase.
Weeks 33-Birth (Almost There!):
The fetus is running out of room in the womb, so movements might decrease but be stronger.
It's gaining weight quickly, preparing for life outside.
Most of the organs are fully developed, getting ready for the big day!
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