By: Carlos Daniel Caicedo & Carlos Eduardo Calle 10c
Slide 2
What is Gestation? Gestation is when a female viviparous*
animal carries an embryo* or fetus. The interval time of a
gestation plus two weeks is called gestation period*. The length of
time plus two weeks that the offspring have spent developing in the
uterus is called gestational age*.
Slide 3
In mammals the gestation period is the period in which the
fetus develops, this starts with the fertilization and ends on the
birth. Smaller species normally have a shorter gestation period
than larger animals: An example is the gestation period of a cat it
normally takes 5865 days while an Elephant's gestation period lasts
645 days. What is gestation period?
Slide 4
In humans the gestation period is normally of nine months.
Factor such as gender can affect the duration of the gestation
period, for us humans a male fetus tends to gestate longer than
female fetuses and multiple pregnancies, tend to take a shorter
time. The ethnicity (race) make the gestation period longer or
shorter.
Slide 5
Gestational age Gestational age is the time measured from the
first day of the woman's last menstrual cycle to the date were the
baby is born, it is measured in weeks. A normal pregnancy can range
from 38 to 42 weeks. Infants born before 37 weeks are considered
premature. Infants born after 42 weeks are considered post mature.
You can determine the gestation age in two ways, before or after
the baby is born: Before birth, growth is determined with
ultrasound by measuring the size of the head, and abdomen.
Slide 6
After the birth, it can be determined by measuring the babys
head circumference, the babys height, condition of skin and hair,
reflexes, muscle tone, posture, and vital signs. Finding the
gestational age is really important because with this doctors can
gather valuable information of expected or potential problems that
the baby could have.
Slide 7
After a female egg is fertilized, the resulting one celled
organism is called zygote. Once the egg is fertilized, the zygote
begins a two week period of rapid cell division and becomes to be a
embryo. The zygote divides with the process of mitosis, in witch
each cell doubles by dividing in two cells. This two week period is
called the germinal period of development. Whats a zygote?
Slide 8
A zygote is a single diploid cell(a diploid cell is cell with
two chromosomes), created through the merging of two haploid cells
(a cell that contains a complete set of chromosomes). The period of
the zygote lasts for about four days. Around the fifth day, the
mass of cells becomes known as a blastocyst (the blastocyst is a
structure formed in the early embryogenesis of mam mals). The
germinal period will last for fourteen days, after this the
embryonic period begins.
Slide 9
Whats a embryo? An embryo is an organism in the early stages of
development which cannot survive on its own. The precise definition
of an embryo varies; in humans, for example, a fertilized egg may
be considered an embryo until around the eighth week of pregnancy,
as the embryo mature it starts to turn into a recognizable form to
the point when people start referring to it as a fetus, especially
in humans.
Slide 10
The term embryo is only used to refer to eukaryote (or
muticellular organisms) organisms. The formation of an embryo
starts at fertilization, when eggs and sperm meet, they form what
is known as a zygote. After fertilization, the zygote starts to
divide, when division begins the zygote turns into an embryo.
Slide 11
Multiple gestations Occurs when two or more fetuses are
conceived at the same time in the same woman. With multiple
gestation, the fetuses are either monozygotic* or dizygotic*. There
is a higher rate of occurrence with use of fertility drugs or
treatments, such as in vitro fertilization.
Slide 12
Monozygotic: during conception, the sperm fertilizes one egg,
which will later split into two or more developing embryos.
Dizygotic multiples: occur when a womans body releases several
eggs, and those eggs are each fertilized by different sperm. The
resulting fetuses are fraternal siblings, and are not
identical.
Slide 13
Social factors which affect gestation Medications and drugs can
also impact embryonic growth. This 8,000 babies were born with
birth defects because their mothers had taken the tranquilizer
Thalidomide. Some races are more prone to teen pregnancy, data
taken by The Guttmacher Institute show that: blacks typically have
126 teen girls become pregnant in every 1,000 girls. Hispanic have
127 teen girls become pregnant in every 1,000 girls. Non-Hispanic
whites average 44 pregnancies per 1,000 girls.
Slide 14
Today researches show that a girl who lives in poverty is more
likely to become pregnant because of teachings and attitudes on
sex, as well as access to contraception.
Slide 15
Enviromental factors which affect gestation Researchers found
that the air quality of the area was worse during the winter
months, and the infants conceived during those winter months saw
the most intrauterine growth retardation. Smoking during gestation
cause aproximately 20 to 30 percent of low-birth weight babies.
Reaserches states that up to 14 percent of preterm deliveries are
due to smoking.
Slide 16
FAQ What is the difference between a pregnancy and gestation?
Pregnancy is the fertilization and development of the offspring in
womans uterus, while gestation is the carrying of the embryo. Why
do all animals have a different gestation period? For most species,
the amount a fetus grows before birth determines the length of the
gestation period. Smaller species normally have a shorter gestation
period than larger animals.
