Transcript Stages of Prenatal Development

STAGES OF PRENATAL
DEVELOPMENT
CHAPTER 9
GERMINAL STAGE
• The first two weeks after conception
• The germinal stage spans the time
from fertilization to implantation in the
wall of the uterus.
• For the first three or four days the mass
of dividing cells moves about the
uterus before implantation.
EMBRYONIC STAGE
• The period of 2 to 8 weeks after
conception.
• Major organ systems begin to take shape,
which is now called the embryo.
• Nervous system, head and blood vessels
form at this time as well
• During the 4th week, the heart starts
beating
FETAL STAGE
• From the 9th week until birth.
• All major organs as well as fingers and
toes develop by the 12th week.
• The fetus grows more than 30 fold in
weight during the 2nd trimester (1 oz. to
2 lbs.)
• The fetus reached the age of viability,
where it could sustain life on its own
outside of the womb.
THREATS TO PRENATAL
DEVELOPMENT
• Maternal malnutrition is related to
premature birth and low birth weight.
• The risk of spina bifida, a neural tube
defect, can be reduced if vitamins
containing folic acid are taken during
pregnancy.
TERATOGENS
• Derived from the Greek root teras,
meaning “monster”.
• Can include;
• Certain drugs taken by the mother
• X-rays
• Environmental contaminants such as lead
and mercury
• Infectious organisms
TERATOGENS
• Can include infectious diseases such as
rubella, which can lead to serious birth
defects (heart disease, mental
retardation, deafness)
• HIV/AIDS and syphilis can be passed from
mother to child during pregnancy.
• Syphilis can lead to liver damage,
impaired hearing and vision and
deformities in teeth and bones.
SMOKING
• Can lead to miscarriage, premature
birth, low birth weight and increased
risk of infant mortality.
• The more the mother smokes, the
greater the risk.
• Maternal smoking has also been linked
to sudden infant death syndrome
(SIDS)
SMOKING
• Maternal smoking can also lead
to;
• Lung problems
• Childhood asthma
• Developmental problems
• Short attention span
• Learning problems
• Behavioral problems
ALCOHOL
• Maternal alcohol use can lead to fetal
alcohol syndrome (FAS).
• Alcohol is also the leading cause of
mental retardation (facial deformities,
underdeveloped upper jaw, widely
spaced eyes).
• There is no established “safe” limit for
alcohol use during pregnancy
DRUGS
• Any drug used during pregnancy,
whether legal or illicit, or any
medication, whether prescribed or
bought over the counter can
potentially harm the fetus.
• Pregnant women should consult their
doctors before taking any medication!