PRENATAL
DEVELOPMENT AND
BIRTH
How did you develop before birth?
Prenatal development
2D Ultrasound
4D Ultrasound
When can you confirm pregnancy?
• Can not be confirmed by blood or urine tests until the
zygote implants in the uterus (about 10 days after
conception).
What are the stages in prenatal development?
• Germinal - 1st 2 weeks
• Embryo – Week 3 to 8 (2 months)
• Fetus – Week 9 to birth
When is the germinal period?
Conception
• First 2 weeks
• Conception
• Zygote
• Implantation
Zygote
How does an embryo
develop?
Primitive streak
• 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)
4 Weeks
8 Weeks
Do you remember?
• What needs to happen for pregnancy to be confirmed?
• About how long after conception does this occur?
• What are the three major stages in prenatal
development?
• How long is the germinal period?
• What ends this period?
• How long is the embryo when it becomes a fetus?
• At how many weeks does this happen?
When is it a fetus?
(9 weeks – Birth)
9th. Week
• 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
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
• Teddy bear with Mother’s heart sounds story
• Responds if mother is fearful or anxious
Labor & birth
Cervical dilation chart
• Labor
• 12 hrs. – first child
• Stages of labor
10 Cm.
• 1st. = Cervical dilation
• 2nd. = Crowning
• Only about 1/3 of zygotes implant
successfully, and additional pregnancies
are lost due to miscarriage and other
factors. (Note: This varies slightly from the
lecture, but does not effect the exam.)
Crowning
What is the Apgar Scale?
• Activity
• Muscle tone
• Pulse
• Heart
• Grimace
• Reflex irritability
• Appearance
• Skin color
• Respiration
• Breathing
• 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
Do you remember?
• When does it become a fetus?
• When is the age of viability?
• What are the five items the Apgar test looks for?
What are some problems and solutions?
What are teratogens?
(Items increasing prenatal abnormalities)
• Types
• Substances (drugs, pollution)
• Conditions (Stress or malnutrition)
• Teratogens = Physical defects
• Cleft palate
• Thalidomide babies (deformed limbs)
Cleft palate
• Behavioral teratogens = Behavioral defects
• Hyperactivity
• Antisocial
• Learning-disabled
Thalidomide baby
• Autism
What triggers harmful teratogens?
• Timing
• Some only cause damage during critical periods
• When organ or body part is most vulnerable
• Before pregnancy
• Avoid drugs (e.g. smoking & 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
• My story
What are the causes & effects of 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
• Effects
• Infant death
• Thinking (cognitive) problems
• Seeing and hearing problems
• In adulthood - higher rates of:
• Obesity
• Heart disease
• Diabetes
What do newborn reflexes do?
• 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
Do you remember?
• What are behavioral teratogens?
• What is an example?
• What is SGA?
• What is the most prevalent cause of it?
• What are the reflexes that aid survival?
• What five reflexes show that the brain and body are
functioning correctly?