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