Birth Defects Flashcards
Birth defect
Abnormality of structure, function or metabolism present at birth that results in physical or mental disabilities or death
How many US babies have birth defects each year?
~120,000 (1 in 33)
Leading cause of death in the first year of life
Birth defects
Congenital defect
Any physical anomaly which is recognizable at birth
Trisomy 21
Down syndrome - mental retardation, characteristic facial features, and often heart defects
Trisomy 13 or 18
Multiple birth defects and often death in first months of life
Achondroplasia
- Single gene defect
- Dwarfism
Cystic fibrosis
- Single gene defect
- Serious disorder of lungs and other organs
Hemophilia
- Single gene defect
- Blood clotting disorder
Teratogens
Environmental substances causing birth defects
Common teratogens
- Alcohol
- Medication
- Infection
How can birth defects be reduced?
- Genetic counselor
- Avoid smoking, alcohol, and drugs
- STD screening
- Folic acid
When does neural tube formation occur
Between 15-28 days of development
Anencephaly
- Upper part of neural tube does not close all the way
- Baby is born w/o parts of brain and skull
Spina bifida
- Occurs anywhere along spine where neural tube does not close all the way
- Physical and mental disability
How can birth defects be diagnosed before birth?
- Blood test
- Ultrasound
- Chorionic villus sampling
- Amniocentesis
When can non-invasive prenatal testing be done?
As early as 7 weeks
Ultrasound in the first trimester
- Establish dates of pregnancy
- Detect heartbeat 7 wks LMP
- Fetal movement 7-8 wks
- Determine number of fetuses
- Diagnose ectopic pregnancy or miscarriage
Ultrasound in second trimester
- Examine fetal anatomy for presence of abnormalities
- Discover sex of fetus at 14 wks
Ultrasound in third trimester
- Monitor fetal growth
- Check amniotic fluid
- Determine fetus and placenta position
When is chorionic villus sampling performed
10-12 wks LMP as placenta is fully functional
Does chorionic villus sampling provide information on neural tube defects
No
When is amniocentesis performed
15-20 wks LMP because amniotic fluid volume is maximized relative to fetus
Indicator of neural tube defect
Alpha-fetoprotein
Amniocentesis
Provides information about neural tube defects, chromosomal abnormalities, and other defects
Arguments FOR prenatal screening
- Pursue interventions
- Plan for child with special needs
- Lifestyle changes
- Identify resources
- Make decision about carrying to term
Arguments AGAINST prenatal screening
- Parents should be accepting regardless of outcome
- Personal, moral, or religious reason
- May pose risk to fetus
Phenylketonuria (PKU)
Babies cannot process phenylalanine (an amino acid found in all foods). A build up causes brain damage and mental retardation.
