When the ovum
meets the sperm during her way to the uterus in the oviduct, fertilization will
occur. Further, a zygote resulted from this fertilization will attach to the
uterus and grows into a fetus. The zygote implantation to uterus wall is under
the influence of estrogen and progesterone. Both of them have the duty to
prepare uterus wall to receive embryo’s implantation.
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| Picture a. Process of embryo's attachment |
After attached
to the uterus wall, fetus will get food from the mother through the placenta. Before
the placenta is formed, the fetus will get food from the corpus luteum. Fetus is
covered with a membrane with a function to protect embryo from dryness and
shakes, and assist the fetus with respiration and excretion. This membrane is
consisted of the saccus vitellinus (vitelline membrane), the amnion, the
chorion, and the allantois. The saccus vitellinus (the yolk sac)
is an emergence place of blood vessels. The amnion is the inner membrane,
adjacent to the embryo, produces the amniotic fluid to protect the embryo from
shakes. The chorion is the outmost membrane that protects the
embryo. The chorionic villi attach to the uterus wall. The allantois
can be found in the fetal circulation with the placenta. The placenta
is an organ that grows in the uterine wall, which derives from the chorion and
the endometrium. The function is to supply food (in the form of glucose and
amino acids) and oxygen for the respiration and throw away the urea and other
waste substances from the fetus to mother’s body.
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| Picture b. A fetus in the womb is protected by the amniotic fluid |
After being
approximately 40 weeks in the womb from the beginning of the last menstrual
cycle, a baby is complete and ready to be born. The hormones that play role
during the birth are relaxin, estrogen, prostaglandin, and oxytocin. Relaxin assists
muscular stretching in the symphysis pubis. Estrogen impedes the progesterone
and helps the uterine wall contraction. The prostaglandin impedes the
progesterone. Oxytocin helps the uterine wall contraction. The parturition
occurs in several stages. The early stage is indicated with the cervical
opening until that a perfect opening is obtained. Further, the stage of baby
expulsion is occurred. The final stage is indicated with the discharge of the
placenta.
The body of a
mother who has just given birth will automatically secrete the lactogen
or prolactine hormone to stimulate the secretion and ejection of
the breast milk. Milk secretion from the mammary glands is called lactation.
With baby’s stimulation and suck, the breast milk will be continuously produced
mammary glands. It is suggested that the breast milk is exclusively given
during the first six months of a baby’s life. The exclusive breast milk is
giving breast milk without additional food such as instant milk, fruit,
porridge, or water.