prenatal growth three main periods of prenatal development
TRANSCRIPT
Prenatal Growth
Three main periods of prenatal development
Germinal period
Embryonic period
Fetal period
Germinal Period: First 14 Days
Zygote begins duplication and division within hours of conception.
• Development of the placenta
• Implantation (about 10 days after conception)
• Organism grows rapidly
The Most Dangerous Journey In the first 10 days after
conception, the organism does not increase in size because it is not yet nourished by the mother.
The Embryonic Period: From the 3rd- 8th Week
Embryo the neural tube later forms the
brain and spine of the CNS. Head takes shape. Eyes, ears, nose, and mouth form. Heart begins to pulsate. Extremities develop and webbed
fingers and toes separate.
Fetus
The third month– Rapid growth with
considerable variation
– Average: 3 months; 100 grams, 100 millimeters
– 3rd month: Neurological sex differences begin
There’s Your Baby For many parents, their first glimpse of their future child is an ultrasound
image. This is Alice Morgan, 63 days before birth.
Fetus4th, 5th and 6th months
Digestive system develops
Fingernails, toenails, and buds for teeth form, and hair grows (including eyelashes)
At the end of 4 months, the fetus, now 6 inches long, looks fully formed but out of proportion—the distance
from the top of the skull to the neck is almost as long as that from the neck
to the rump.
Fetus
Brain Experiences rapid growth
From brainstem to midbrain, to cortex
Develops many new neurons (neurogenesis) and synapses (synaptogenesis)
Begins to regulate basic bodily functions as entire CNS becomes responsive
Fetus
Last three months Involves expansion and
contraction of lungs
Includes final maturation of heart valves, arteries, and veins
Provides time for extensive growth and folding in cortex
One of the Tiniest Rumaisa Rahman was born after 26 weeks and 6 days weighing
only 8.6 ounces (244 grams). She has a good chance of living a full,
normal life.
Prenatal Growth of the Brain
Fetus
Age of viability• Age at which a preterm
newborn may survive outside the mother's uterus if medical care is available
• About 22 weeks after conception
• Brain is able to regulate basic body functions (e.g., breathing)
Harmful Substances (page 110)
Teratogens Any agent or condition,
including viruses, drugs, and resulting in birth defects or death
Behavioral Teratogens Agents and conditions that can
harm the prenatal brain, impairing the future child's intellectual and emotional functioning
Critical periods matter!
Risk Analysis: How Much Is Too Much?
Threshold effect Certain teratogens are relatively harmless until
exposure reaches a certain level. Thresholds are controversial
Alcohol consumption Embryo exposed to heavy drinking can develop
fetal alcohol syndrome (FAS). FAS is more apparent when women are poorly
nourished and cigarette smokers.
Genetic vulnerability
Some zygotes carry genes that make them vulnerable.
Male fetuses are more vulnerable to teratogens than
female ones.
Mother’s genes affect the prenatal environment she
provides (example, anxiety)
“prenatal development is not a dangerous period to be
feared as much as a natural process to be protected.”
Birth About 266 days later… Oxytocin starts labour and prepares
fetus for delivery Birthing process is largely cultural
The Newborn’s First Minutes
Newborns Usually cry spontaneously Color changes from bluish to pinkish Eyes open, fingers grab, toes stretch
Medical Assistance
Surgery: Cesareans• Are controversial
• Involve surgical birth
• Vary by rates and reasons for use
• Present advantages for hospitals; more complications after birth
From Day One For various reasons, some
countries have much higher rates of cesarean deliveries than others.
Medical Assistance
Epidural Injection in particular part of spine to alleviate
pain. Often used in hospital births (63% of women)
Low Birth weight and the Mother
Low Birthweight (LBW): A body weight at birth of
less than 5½ pounds (2,500 grams). Become high risk infants and children
Maternal behavior• Maternal health and illness• Malnutrition• Maternal drug use before and during pregnancy
Fathers and others• Father attitudes and behaviors• Hispanic paradox
The New Family: Mothers
About half of all women experience physical problems after birth.
Between 8 and 15% of women experience postpartum depression. https://
www.youtube.com/watch?v=yH3WMQO-ooU 5 min
Feelings of sadness and inadequacy May involve struggles with adequate baby
care Varied causes
The New Family: Fathers
Not only fathers, but the entire social network and culture are crucial influences
Father's role
• Helping mother stay healthy
• Helping mother manage stress
Bonding
Parent-infant bond• Bonding involves strong, loving connection that
forms as parents hold, examine, and feed the newborn.
• Early skin-to-skin contact is not essential for human bonding.
The Importance of Close Contact
Birth complications can have lingering impact on later life.
Mothers and fathers should help with early caregiving if newborn must stay in the hospital.
Research confirms benefits of skin-to-skin contact