Prenatal Development Flashcards
Prenatal Development
development
of an organism from conception
through birth
Stages of Prenatal Development
Germinal Stage
Embryonic Stage
Fetal Stage: Week 9 to Birth
Germinal Stage
Cell differentiation and implantation occur
– CRITICAL POINTS:
• Hormonal changes make implantation optimal at 9
days, but unlikely AFTER 9 DAYS
• Upon implantation, embryo begins to take nutrients
from mother’s blood, and is now vulnerable to
TERATOGENS
– Excessive alcohol consumption especially dangerous
• Hormonal changes cause fatigue, nausea, and swollen
breasts
Embryonic Stage
Week 3 through 8: – Differentiation continues – CRITICAL PERIODS OF DEVELOPMENT: • Differentiation and growth occur rapidly • Essential structures form • Embryo is highly vulnerable to: – GENETIC ABNORMALITIES – ENVIRONMENTAL INFLUENCES THAT AFFECT CELL DIVISION AND/OR DAMAGE EMBRYO » Miscarriage (spontaneous abortion) » Brain damage, birth defects, etc. – Organogenesis; embryo is now a fetus
Fetal Stage: Week 9 to Birth
Period lasting approx 30 weeks of rapid growth and
development
– Weeks 9-12: sex organs develop
• Usually can be seen on ultrasound at 14 weeks, but not truly accurate
until 20 weeks
– Weeks 17-20: heartbeat can be heard
• Mother can feel movement
• About 5 inches long
– Week 24: rapid weight gain (“baby fat”)
• About 10 inches long
– CRITICAL POINT: Weeks 26 to 28
• Fetus is now viable if born premature due to mature lungs
• Fetus can turn head toward bright light outside womb
• Fetus sucks thumb, hiccups, and sleeps
– Weeks 28 to 40:
• Rapid weight gain (5 lbs)
• All organ systems become fully formed
• Brain develops rapidly
Chances of getting pregnant
– 20-24 years: 20% probability with unprotected sex
– 30 years: 15%
– 35 years: <10%
Infertility
– Approx. 1/3 attributed to fertility problem in female
– Approx. 1/3 attributed to fertility problem in male
– Approx. 1/3 attributed attributed to both or unexplained
Factors that compromise sperm health
– Age – Workplace toxins – Tobacco (smoking and chewing) – Alcohol, Illicit drugs – Heat – Stress – Other factors that may reduce production or quality of sperm
Factors affecting ova and ovulation
– Ovulation Disorders – Fallopian tube damage (e.g, STD’s, ectopic pregnancy) – Endometriosis – Stress – Illness – Toxins – Tobacco, alcohol, drug use, caffeine – Weight: unhealthy BMI – AGE
TERATOGENS
Environmental factors that can cause
birth defects
Example: Thalidimide •Drug used to treat nausea in pregnant women in the 1950’s and 60’s •Causes shortening of limbs; “Flipper-like” arms
Critical Periods
• Vulnerability of fetus to teratogens varies throughout pregnancy – Germinal stage: lower risk • No nutrient sharing • Exposure likely fatal – Embryonic stage: highest risk • Nutrient sharing during organogenesis • Exposure =major malformations/damage – Fetal stage: moderate risk • Exposure unlikely to be fatal • Can cause malformation and mental retardation
Alcohol
Alcohol crosses placenta, disrupts cell division, and
kills fetal cells
• Reduces blood flow through placenta to fetus
• Exposure during pregnancy can cause:
– Damage to brain/central nervous system
– Physical deformities
– Growth retardation
– Miscarriage/death
– FETAL ALCOHOL SYNDROME
– Inattention, impulsivity, learning problems
FETAL ALCOHOL SYNDROME
FAS
Growth deficiency • Head and facial deformities • Dysfunction of CNS – Mental retardation – Poor motor fx: Cerebral palsy – Inattention, impulsivity, poor executive functioning
How much alcohol is too much
• FAS usually occurs when mother is:
– Chronic alcoholic (6 or more drinks per day)
– Binge drinker (4+ drinks at one time/1x per wk)
• Some studies suggest one drink per week can result in
Inattention, hyperactivity, and increased aggression
– One episode of binge drinking can cause brain damage
• Best practice: abstinence during pregnancy
– Even when trying to conceive!
Cocaine
prematurity, growth retardation,
malformation in brain, intestines, genitals,
etc., impaired sensory fx, increased arousal,
decreased autoregulation, higher risk of LD,
ADHD, language problems
Smoking
reduced blood supply to fetus; abnormal brain development; prematurity; poor nutrition (appetite suppressant); increased risk of LD, ADHD; spontaneous abortion, stillbirth, neonatal death
Maternal Illness
Infectious Diseases: Rubella, Chicken Pox, etc.
• Sexually Transmitted Diseases: cross placenta and
can cause birth defects or infectious disease in fetus
• HIV/AIDS; Syphillis
• HERPES SIMPLEX VIRUS
• 2 OUT OF 4 AMERICANS ARE INFECTED
– 30-50% of college students
• CAN CAUSE MISCARRIAGE, BRAIN DAMAGE, MR, DEATH
• MOST INFECTION OCCURS AT BIRTH
– Mothers with active genital herpes at time of birth have high
risk of transmission, therefore, Cesarean section is
recommended
Some surprising teratogens
• Retinoids: Vitamin A
– Retinol, Oral Accutane; Tretinoin; Retin-A
• X-rays; laser hair removal
• Some chemical hair dyes, skin bleaches, nail products
– Research is inconclusive; exposure would have to be high/chronic
• Hot tubs (heat over 100-105 degrees F)
• Some antianxiety drugs: benzodiazepines
• Some antidepressants: MAO inhibitors
• Some mood stabilizers: Lithium
– Anticonvulsant mood stabilizers: valproate, carbamazepine
• Other drugs: allergy medicines; aspirin; cold remedies,
Maternal Age
Mothers under 15 and older than 40: higher
risk of low birth weight
• Young mothers: GxE Interaction
• Non-Hispanic black mothers have higher risk of LBW
across reproductive lifespan→ GxE Interaction
• Late 30’s and early 40’s:
• Higher risk of high BP, gestational diabetes, Down
syndrome
teratogenic food-borne pathogens
– Salmonella: Raw or undercooked chicken and eggs:
– Listeriosis: Raw or undercooked meats, unpasteurized dairy;
no contact with livestock
– Toxoplasmosis: Raw or undercooked meat & pork; raw
improperly washed vegetables; cats & kitty litter boxes
– Botulism: improperly stored or canned foods
How to have a healthy pregnancy
• Start before you are pregnant, when you are trying to
conceive:
– Healthy balanced diet: most pregnant women
need only 200-500 extra calories per day
- Avoid caffeine (1 cup/day is ok) and alcohol
• Maintain safe food preparation practices
Take prenatal vitamins:
– Less than 10,000 IU of Vitamin A
– At least 400 mcg (.4 mg) of Folic Acid or Folate
• Insufficient FA during first 28 days of pregnancy can lead to MAJOR
neural tube, brain, and spine defects, including Spina Bifida
– Iron and calcium are very important
• Should include foods rich in all three
• Exercise and reduce stress
• Brush your teeth and floss!
• Get good prenatal care
Birth: Stage 1: Dilation
Uterine contractions begin • Cervix begins to open; must dilate to 10 cm •Baby begins descent in birth canal, and head presses up against cervix •Can last 6-14 hours
Birth: Stage 2: Delivery
• Baby moves through birth
canal and is BORN!
• Lasts 30 min to 2 hrs
Birth: Stage 3: Afterbirth
- Uterus continues to contract in order to expel
the placenta
– Takes about 15 minutes
• Fun facts:
– Recently, women have begun to freeze their
placenta for later use
• Plant a tree with it
• Make a “print”
• Ingest it to prevent post-partum depression??
Psychological Adjustments to Having a
Newborn
• Parents much adjust to changes in: – Relationship: couplehood vs parenthood • Free time, romance, sex, attention – Work / Career – Finances – Daily hassles/stress – Physical changes: • Fatigue, breastfeeding, sleep deprivation – Child Temperament and individual needs – Other siblings, older dependent parents
Qualities of a healthy “newborn” family
• Well-developed coping skills • Frequent communication • High degree of warmth and positive interaction • Realistic expectations • Temperament match • External support
The Ghosts in the Nursery
• Becoming a parent can often make one reflect on their own parents – Childhood – Experience of parenting – Can influence: • Parenting style • Attitude toward role • Attachment
Dealing with Sibling Rivalry
• Prepare child for birth of sibling
– Use age-appropriate language and concepts
– Talk about child’s feelings about having a new
baby
– Discuss how life will change
• Set aside one-to-one time with child, even
when baby is born
– Model pos. ways to get attention and praise
• Ask older sibling for help with baby
