Pregnancy, also known as gestation, is the time during which one or more offspring develops inside a woman. A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy can occur by sexual intercourse or assisted reproductive technology.

1. BARKATULLAH UNIVERSITY
DEPARTMENT OF ZOOLOGY & APPLIED
AQUACULTURE
•TOPIC
•Physiologyof pregnancy
•Placentalhormonesand
paturition By....
Shallu kotwal
M.Sc. 2nd sem zoology

2. CONTENTS
1. Physiology of
pregnancy
• Introduction
• Physiological stages of
pregnancy
2. Placental Hormones
• Introduction
• Hormones

3. INTRODUCTION
Pregnancy is defined as the course
of embryo and fetal growth and
development in uterine. It begain
at the fertilization (fusion of male
and female gametes) and end the
delivery of the fetal and its
attachments.
Pregnancy last
about 40-41weeks i.e; 280days
,counting from the first day of the

4. PHYSIOLOGICAL STAGES
OF
PREGNANCY
The weeks are grouped into three
trimester.
1. First trimester (week 1-week 12).
2. Second trimester (week 13-week
28).

5. FIRST TRIMESTER
(WEEK 1- WEEK 12).
The first trimester of pregnancy is
when The major organ systems of
the foetus begin to develop.By the
eighth week after fertilization all
organs are present .
In this trimester the
body undergoes many changes.
Hormonal changes affect almost
every organ system of the body.
Other changes may include:-
• Extreme tiredness.

6. SECOND TRIMESTER
(WEEK 13-WEEK 28)
This is a period of rapid relative
growth.It is often the most pleasant
for women.Their body has now
conpletely adjusted to the
pregnancy.At this point the child’s
movements are quite noticeable.
This period include following
changes:-
• Body aches, such as back
,abdomen,thigh pain.
• Strecth marks on abdomen.

7. THIRD TRIMESTER
(WEEK29 -WEEK40)
During the final trimester,the child
matures quickly and gets bigger and
heavier.Many women find breathing
difficult at this stage.This is because
the baby is getting bigger and it is
putting more pressure on the organs of
the mother.
New body changes are:-
• Heartburn ,sleeping trouble etc.
• Shortness of breath.
• Swelling of ankles,fingers and face.

8. PLACENTAL HORMONES
Introduction
The placenta is a large temporary
organ that develops during
pregnancy. It is attached to the
wall of the of the uterus, usually
at the top or side. The umbilical
cord connects the placenta to the
baby.Blood from the mother
passes through the placenta. The
placenta also filters out
substances that could be harmful
to the baby and removes carbon
dioxide and waste products from

9. HORMONES
ESTROGEN
• Produced in corpus luteum.
•Produced by placenta after
12weeks.
• Responsible for growth particularly
of uterus and breasts

10. PROGESTERONE
•Maintains uterine lining.
•Inhibits uterine contraction until
uterus is prepared for labor.
•Produced in corpus luteum.
•Help prepare mammary glands for
lactation.

11. HUMAN CHORIONIC
GONADOTROPIN
•It maintains the corpus luteum of
pregnancy to secrete estrogen and
progesterone.
•Helps for pregnancy diagnosis tests.
•Stimulates the growth of breast gland.

13. PARTURITION
Parturition refers
childbirth the process
of delivering the baby
and placenta from the
uterus through vagina
to the outside world. It
is also called labor and
delivery.

14. STAGES OF PARTURITION
1.Stage ofDilation
2.Stage of expulsion
3.Stage of placental

15. STAGE OF DILATION
• The first stage of parturition starts
with the onset of labor. It continues
until the cervix is fully dilated. Thie
dilation is divided into two phases.
1. LATENT PHASE:- The cervix is 0 to
4cm dilated.
2. ACTIVE PHASE:- The cervix is 4 to
10cm dilated.
This stage typically lasts
around 6-12 hours.

16. STAGE OF EXPULSION
The second stage of parturition
starts at full dilation and
continous until birth. This stage
also has two phases:-
1.PASSSIVE PHASE:- The baby’s
head moves down through the
vagina.
2.ACTIVE PHASE:- The mother
feels a need to push, or
contract the abdominal

17. STAGE OF
PLACENTAL
The time (5-30
minutes or more) after
delivery until the
placenta or “
afterbirth” is expelled
by powerful uterine
contractions is the
placental stage.