04-PRENATAL DEVELOPMENT AND BIRTH

Prenatal development

Pregnancy confirmation• Can not be confirmed by blood or urine tests until the

zygote implants in the uterus (about 10 days after conception).

Prenatal Development• Germinal - 1st 2 weeks• Embryo – Week 3 to 8 (2 months)• Fetus – Week 9 to birth

Germinal period• First 2 weeks

• Conception• Zygote• Implantation

Embryo• Week 3 – 8 (2 months)• First - “Primitive streak” develops = neural tube = brain &

spinal column• 4th. Week

• Head takes shape• Early heart begins to pulsate

• 5th. Week• Arm & leg buds develop• Webbed fingers and toes develop

• 8th. Week• 1 inch long• Has all basic body parts and organs (except sex organs)

• Embryo – 4 weeks

• Embryo – 5 Weeks

• Embryo – 7 weeks

• Embryo – 8 Weeks

Fetus (9 weeks – Birth)

9th. Week• Male gene triggers development of male organs

• If not, female organs develop

Fourth, fifth, sixth months• Heartbeat becomes stronger• Digestive and excretory systems develop• New neurons & synapses develop

• Up to one 500,000 brain cells per minute are created • Age of viability

• Can possibly survive outside the mother (with intensive medical care)• 22 weeks

Fetus (9 weeks - birth)• Final three months• Lungs begin to expand and contract (fetal respiration)

• Breathe using amniotic fluid as a substitute for air• Fetus

• Grows and moves more• Startles and kicks at a loud noise• Becomes used to mother’s heartbeat and voice• Responds if mother is fearful or anxious

Birth• Labor

• 12 hrs. – first child• Stages of labor

• 1st. = Cervical dilation• 2nd. = Crowning

• About 31% of zygotes survive to be born

• Birth in U.S.

• Birth in Peru

• Birthing chair - Egypt

Apgar Scale• Color• Heart• Reflex• Muscle• Breathing (Respiration)• Done twice – 1 & 5 minutes after birth to determine if

immediate medical care is needed• Score = 0,1,2 for each item• Total of 7 or above is desired

Problems and Solutions

Teratogens: (Items increasing prenatal abnormalities)• Types

• Substances (drugs, pollution)• Conditions (Stress or malnutrition)

• Teratogens = Physical defects• Cleft palate• Thalidomide babies (deformed limbs)

Behavioral teratogens = Behavioral defects

• Hyperactivity• Antisocial• Learning-disabled

Teratogens: Critical factors

• Timing• Some only cause damage during critical periods

• When organ or body part is most vulnerable• Before pregnancy

• Avoid drugs (e.g. alcohol)• Fetal alcohol syndrome

• Better diet• Immunizations

• Problem – Half of births are unplanned• Threshold effect

• Some are harmless until they “cross the threshold” and become harmful• Alcohol, tobacco, and marijuana do more harm in combination

• This lowers the threshold for each

• Genes – May increase birth defects

Low birth weight• Causes

• Born preterm• Born small for gestational age (SGA)

• Maternal or fetal illness• Drug use

• Every psychoactive drug• Tobacco (Most prevalent cause)• Malnutrition

• Consequences• Infant death• Thinking (cognitive) problems• Seeing and hearing problems• In adulthood - higher rates of:

• Obesity• Heart disease• Diabetes

Newborn reflexes• Reflex = involuntary response to a stimulus• Reflexes that aid survival

• Breathing – Maintains oxygen• Shivering – Maintains temperature• Sucking – Manages feeding

• Rooting – Searching for a nipple

• Reflexes that show the state of brain and body functions• Babinski reflex – Toes fan upward when feet are stroked• Stepping reflex • Swimming reflex• Palmer grasping reflex• Moro reflex - Being startled

• Sucking reflex

• Grasping reflex

• Stepping reflex