The document summarizes key aspects of human birth, including: - Gestation typically lasts 280 days, during which the placenta secretes progesterone to maintain pregnancy. Abnormalities can cause miscarriage or preterm birth. - Around 12 weeks, most organs have developed and the fetus grows for the rest of gestation inside the amniotic sac filled with fluid that protects and cushions the baby. - Near birth, hormones from the baby's pituitary stimulate its adrenal glands to release corticotropin, crossing the placenta and causing a drop in the mother's progesterone. This triggers the mother's pituitary to release oxytocin, inducing labor contractions that push the baby through

1. BIRTH
1 DEC

2. • In humans total Gestation period (pregnancy) is 280 days.
• Once Placenta is established it start secreting Progesterone hormone to
maintain pregnancy.
• Any abnormality in it’s secretion could result in miscarriage or premature
birth.
• Human embryo is enclosed within the AMNIOTIC SAC filled with amniotic
fluid.
• FUNCTION OF AMNIOTIC FLUID: it acts as shock absorber and
protects the developing baby.
Previously it was secreted by corpus luteum
The inner membrane, the amnion, contains the amniotic
fluid and the fetus. The outer membrane, the chorion,
contains the amnion and is part of the placenta.

3. •HORMONES FOR LACTATION:
• 1. During gestation period, pituitary glad secrets
LEUTROTROPHIC Hormone or PROLACTIN.
• 2. Placenta also secrets Human Placental Lactogen
• Both hormones prepare body for lactation.
a protein hormone produced by the pituitary gland of mammals that acts with other
hormones to initiate secretion of milk by the mammary glands
This hormone breaks down fats from the mother to provide
fuel for the growing baby. It can lead to insulin resistance and
carbohydrate intolerance in the mother.

4. •FETUS: From beginning of the 3rd month human embryo is
called as fetus.
• Organ Development: Most of the organs develop by
the 12th week of pregnancy and for the rest of the
gestation period growth of the fetus occur.
•THE INTIALCAUSEOF BIRTH:
• It was thought that level of progesterone when
decreases in the body of mother stimulates birth but
it was later discovered that:
• The cause of birth are actually hormones
released by Pituitary of the baby.

5. •ROLE OF HORMONES IN BIRTH:
1. The ACTH from Baby’s pituitary stimulates fetal’s
Adrenal Gland to release Corticotropic hormone (to
fight stress).
2. The Corticotropic hormone cross placenta and
enters mother’s body and cause drop in
progesterone level.
3. This decrease in progesterone stimulate pituitary
of mother to produce OXYTOCIN hormone.
4. OXYTOCIN induces labor pain by contraction of
uterus walls.
5. The release of oxytocin occurs in waves and thus
these waves provide force to expel baby out of body
through VAGINA.

6. • The cervix dilates (expands) and uterus contraction in
form of waves expand from top towards the bottom of
uterus and pushes baby downward resulting in delivery.
• Once baby is delivered the Umbilical cord is ligated and
baby is released from mother’s body.
•AFTER BIRTH:
•Within 10-45 min after birth the uterus contracts
and separates the placenta and it passes out
through vagina. This is called after birth.

7. •BLOOD LOSS:
• Bleeding through out this period is controlled by
contraction of SMOOTH MUSCLE FIBRES which
surrounds all uterine blood vessels supplying blood
to placenta.
• Average blood loss is about 350 cm.