Pregnancy typically lasts about 40 weeks and is divided into three trimesters. The first trimester lasts until 12 weeks and includes fertilization and implantation. In the second trimester from weeks 13 to 27, major organs develop and movement can be felt. The third trimester from weeks 28 to 40 includes further physical development and growth until birth.

1. Pregnancy

2.  Pregnancy is measured in trimesters from the first day
of your last menstrual period (LMP) and normally lasts
about 40 weeks from conception to the birth of the
baby. This time is roughly divided into 3 periods: the
first trimester, second trimester, and third trimester.

3. The Three Stages of
Pregnancy
 The first trimester is measures from conception to
about the 12th week of pregnancy. The second
trimester is from 13 to 17 weeks and the third trimester
is from 28 weeks of pregnancy until birth.

4. First Trimester
 Fertilization (About 2 weeks after the first day of the last menstrual period): The mother's body
releases an egg, which is fertilized by a sperm. The fertilized egg has the 46 chromosomes
needed to determine height, hair color, and sex. The egg begins to divide, and begins its trip
down the mother's fallopian tube toward the uterus.
 Implantation (About 5-7 days after fertilization): The egg attaches to the lining of the uterus
during the first trimester of pregnancy. The fertilized egg begins to grow and doubles in size
every day. The placenta and umbilical cord begin to form and carry nourishment and oxygen to
the fetus and carry waste away

5. Week 4
 Week 4 (2 weeks after conception): This is about the
time that the mother misses her period. The embryo is
about 1/100 of an inch long at this time. The baby has a
spinal cord, and is dividing into three layers that will
become the different organs and systems in the
embryo.

6. Week 6
 (4 weeks after conception): The embryo is about 1/6
inch long.
 Limb buds, which will become the legs and arms begin
to appear.
 The embryo’s brain and heart have begun to form

7. Second Month
 At the beginning of this month, the embryo is about 1/2
inch long and weighs a fraction of an ounce. The heart
beats with a regular rhythm
 By the end of the second month, all of the major body
organs and body systems have begun to develop.
 The face and eyelids have formed
 The arms and legs begin to grow longer and the fingers
and toes have begun to form.

8. Third Month
 The embryo is now officially called a fetus, and will be completely
formed by the end of this month.
 The fetus is beginning to move its hands and legs, and opening
and closing its mouth.
 Fingers and toes are now distinct, and hair is beginning to form on
the head.
 By the end of this month, the fetus will be about 4 inches long and
weigh just over an ounce.
 The external sex organs show if the fetus is male or female
 Eyelids close to protect the developing eyes and will not open
again until the 28th week

9. Second Trimester
 The uterus, the muscular organ that holds the
developing fetus, can expand up to 20 times its normal
size during pregnancy.
 Although the fetus begins to move and takes
recognizable human shape during the first trimester, it
is not until the second trimester that movement of the
fetus, referred to as “quickening”, can be felt.

10. 16 weeks
 The muscle tissue and bone continue to form, creating
a more complete skeleton
 Skin begins to form
 The fetus reaches the length of about 4-5 inches and
weighs almost 3 oz

11. 20 weeks
 The fetus is covered by fine hair and eyebrows,
eyelashes, fingernails, and toenails have formed
 the fetus can hear and swallow

12. 24 Weeks
 Taste buds form on the fetus’s tongue
 Footprints and fingerprints have formed
 The fetus sleeps and wakes regularly
 The fetus stores fat and has become about 1.5 pounds

13. Third Trimester
 There is head engagement in the third trimester, that is,
the fetal head descends into the pelvic cavity so that
only a small part (or none) of it can be felt abdominally.
The perenium and cervix are further flattened and the
head may be felt vaginally. Head engagement is known
colloquially as the baby drop, and in natural medicine
as the lightening because of the release of pressure on
the upper abdomen and renewed ease in breathing.
However, it severely reduces bladder capacity,
increases pressure on the pelvic floor and the rectum

14. 32 Weeks
 The fetus’s bones are fully formed, but still soft
 The eyes can open and close and sense changes in
light
 The lungs are not fully formed by breathing movements
occur

15. 36 Weeks
 The protective waxy coating called vernix gets thicker
 Body fat increases and the fetus is now 16- 19 inches
long and weighs about 6 pounds

16. 37-40 Weeks
 By the end of 37 weeks the fetus is considered full
term.