Development of baby inside mothers womb .

1. Baby
The word baby might be used to refer any child from birth to age 4.
Newborn or Neonates : Newborn usually refers to babies from birth to 28 Days of
age.
Infants : Infants are babies from two months to one year old
Toddler : A toddler is a child between the ages of one and three. some people
may consider toddlers to be 18 months old to 3 years old, and a 4 year old might
be considered a preschooler.

2. Fetal development
Pregnancy is measured in trimesters from the first
day of last menstrual period, totaling 40 weeks.
 The first trimester of pregnancy is week 1
through week 12, or about 3 months.
 The second trimester is week 13 to week 27 &
 The third trimester of pregnancy spans from
week 28 to the birth.

3. Zygote
The zygote is the very first stage of life and starts after the union of egg and
sperm.
About 24 hours after the fusion, the first division of the new cell happens, and
it is no longer called zygote. The embryonic period begins.

4. Embryo
The embryo is defined as the developing pregnancy from the time of fertilization
until the end of the eighth week of gestation.

5. Fetus
The unborn young after 8 weeks of conception until birth is called fetus.

6. First Trimester :
Week 1 and 2 : Getting ready
The first week of pregnancy starts with the first day of a woman's last menstrual
period. She is not yet pregnant. During the end of the second week, an egg is
released from an ovary. This is when they are most likely to conceive if you have
unprotected intercourse.

7. Week 3 : Fertilization
The sperm and egg unite in one of the fallopian tubes to form a one-celled entity
called a zygote. Soon after fertilization, the zygote travels down the fallopian tube
toward the uterus.

8. Week 4 : Implantation
By the time it reaches the uterus, the rapidly dividing ball of cells — now known as
a blastocyst — has separated into two sections.
The inner group of cells will become the embryo. The outer group will become the
cells that nourish and protect it.

9. Week 5 : The embryonic period begins
The fifth week of pregnancy, or the third week after conception, marks the
beginning of the embryonic period. This is when the Fetus's brain, spinal cord,
heart and other organs begin to form.
By the end of this week, your fetal is likely about the size of the tip of a pen.

10. Week 6 :The neural tube closes
Growth is rapid in this week. Embryo's body
begins to take on a C-shaped curvature.
In this stage neural tube close and its heart
starts pumping blood.
Week 7 : Embryo’s head develops
Embryo’s brain and face are rapidly developing. Tiny
nostrils become visible, and the eye lenses begin to form.
The arm buds that sprouted last week now take on the
shape of paddles.
By the end of this week, it might be a little bigger than
the top of a pencil eraser

11. Week 8 : Embryo’s eyes are visible
 Arms and legs are growing longer, fingers have begun to
form & eyes are visible. The upper lip and nose have
formed.
 By the end of this week, your Fetus might be about 1/2 inch
(11 to 14 millimeters) long
Week 9 : Fetal toes form
Arms grow, develop bones and bend at the elbows. Toes
form and eyelids and ears continue developing.
By the end of this week, your it might be about 3/4 inch (20
millimeters) long.

12. Week 10 : Neck begins to develop
The neck begins to develop and fetal eyelids begin
to close to protect his or her developing eyes.
Week 11 : Fetal genitals develop
At this stage the fetus maybe about 2 inches (50 millimeters) long from crown to
rump and weigh almost 1/3 ounce (8 grams)
Week 12 : Fetal fingernails develop
At this stage fetal face has a human profile.
By now it might be about 2.5inches (60 millimeters) and weigh
about 1/2 ounce (14 grams).

13. Week 13 : Urine forms
Week 14 : Fetal sex becomes apparent
Red blood cells are forming in fetus spleen. For girls, ovarian follicles
begin forming. For boys, the prostate appears.
By now your fetus might be almost 3 1/2 inches (90 millimeters) long
and weigh about 1 1/2 ounces (40 grams).
Week 15 : Fetal skeleton develops bones
Second Trimester : Week 13-27

14. Week 16 : Fetus can make sucking motions
Fetal eyes have begun to face forward and slowly move.
Ears are close to reaching their final position. They might
be able to make sucking motions with his or her mouth.
It's movements are becoming coordinated and can be
detected during ultrasound exams.
Week 17: Fat accumulates
Toenails have begun to develop and fat stores begin to develop under it's skin.
The fat will provide energy and help them warm after birth.

15. Week 18: Fetus begins to hear
Ears begin to stand out on the sides of his or her head They might begin to hear.
By now it might be 5 1/2 inches (140 millimeters) long and weigh 7 ounces
(200 grams).
Week 19: Fetal uterus forms
A greasy, cheese-like coating called vernix caseosa begins to cover fetus. The
vernix caseosa helps protect delicate skin from abrasions, chapping and hardening
that can result from exposure to amniotic fluid.
For girls, the uterus and vagina might begin to form this week.

16. Week 20: The halfway point
Halfway of pregnancy or 18 weeks after conception, pregnant women might be
able to feel fetal first movements, also known as quickening .
Week 21: Fetus can swallow
Week 22: Fetal hair becomes visible
Fetus completely covered with a fine, down-like hair called lanugo. The lanugo
helps hold the vernix caseosa on the skin. It’s eyebrows might be visible.

17. Week 23: Fingerprints and footprints form
Skin is wrinkled, more translucent than before and pink to red in color.
This week fetus begins to have rapid eye movements. Fetus's tongue will soon
develop taste buds. Fingerprints and footprints are forming. For boys, the
testes are descending from the abdomen. For girls, the uterus and ovaries are
in place — complete with a lifetime supply of eggs.
Week 24: Real hair grows
Week 25: Fetus responds to Voice
Fetal hands and startle reflex are developing. They
might be able to respond to familiar sounds, such as
your voice, with movement.

18. Week 26: Fetal fingernails develop
Fetal lungs are beginning to produce surfactant, the substance that allows the
air sacs in the lungs to inflate — and keeps them from collapsing and sticking
together when they deflate.
By now they might be 9 inches (230 millimeters) long and weigh nearly 2
pounds (820 grams).
Week 27: 2nd trimester ends
This week marks the end of the second trimester. At 27 weeks, or 25 weeks
after conception, your Fetus's lungs and nervous system are continuing to
mature — and he or she has likely been growing like a weed

19. Third Trimester : Weeks 28-40
Week 28:Fetal eyes open
Week 29: Fetal bones are fully developed
Though in this stage fetal bones are fully developed, but they're still soft and
pliable.
Week 30: Fetal eyes are wide open
Fetal eyes are wide open a good part of the time.
They might have a good head of hair by this week.
Red blood cells are now forming in their bone marrow.

20. Week 31: Nervous system development continues
Week 32: Fetus practices breathing
Thirty-two weeks into pregnancy, or 30 weeks after conception, Fetus's
toenails are visible. Although their lungs aren't fully formed, he or she
practices breathing. Their body begins absorbing vital minerals, such as iron
and calcium from the intestinal tract. The layer of soft, downy hair that has
covered skin for the past few months — known as lanugo — starts to fall off
this week
Week 33: Fetus detects light

21. Week 34: Fetal fingernails grow
Week 35: Rapid weight gain begins
33 weeks after conception, Fetus's limbs are becoming chubby and
gaining weight rapidly — about 1/2 pound (230 grams) a week for the next
month.
Week 36: Fetus takes up most of the amniotic sac
Week 37: Fetus is early term
Thirty-seven weeks of pregnancy, or 35 weeks after conception, Fetus will be
considered early term. Their organs are ready to function on their own.
To prepare for birth, their head might start descending into mother’s pelvis.

22. Week 38: Fetus develops a firm grasp
Week 39: Placenta provides antibodies
Thirty-nine weeks into pregnancy, or 37 weeks after conception, Fetus's chest is
becoming more prominent. For boys, the testes continue to descend into the
scrotum.
The placenta continues to supply antibodies that will help fight infection after
birth.
Week 40: Pregnancy due date arrives
At this stage they might be about 18 to 20 inches (450 to 500 millimeters) long and
weigh 6 1/2 pounds (2,900 grams) or more. Remember, however, that healthy
babies come in different sizes. Don't be alarmed if due date comes and goes
without incident. It's just as normal to deliver a Fetus a week or two late — or early
— as it is to deliver on your due date.

24. Adnan-Ul-islam
B.Pharm.(Hons)
adnan.ru.bd@gmail.com