Unit 4 - Part B - Prenatal Developmental Concerns

Teratogens

environmental agent that causes harm to embryo or fetus

• can cause birth defect or death

Factors of teratogen impacts

1. developmental stage of fetus

   • epigenetic crisis period (3-8 weeks; time or particular susceptibility to great harm because vital tissues are being formed

2. not all organisms are effect in the same way

   • some infants are affect more than others (mystery)

3. extent of damage may be dependent on physiological state of mother

   • healthier mom may be able to help fetus fight effects of possible teratogen

4. ↑ amount of teratogen exposure = ↑ extent of damage

5. teratogen might have mild effect on mother but severe effects on developing fetus

6. developmental delays may be only after delay and be recognized only after the child begins school

Internal (maternal) factors

• maternal age

• nutrition

• Rh incompatibility

• Mother’s emotional state

• genetic factors

Maternal age

>35 or <18 are more likely to have difficulties

• >35 ↑ risk of infant with a form of defect and ↑ likely of infant with down syndrome

• Parity

Parity

number of children previously born to a mother

• if they have babies in their ‘prime’ they the risk of having an infant with down syndrome after 35 decreases

Nutrition

on average mothers need to consume +300cal/day

• sufficient weight gain during pregnancy depends on pregravid (original) weight

• prenatal malnutrition can increase risk of difficulties and deformities

• “grandmother” effect

Standards to sufficient weight gain during pregnancy

ideal weight gain should be ~25-35lbs

• if pregravid is 20% above ideal; weight gain should be ~15-15lbs

• if pregravid is 10% lower than ideal; weight gain should be between 28 and 40 lbs

Causes of prenatal malnutrition

placental factors

• problem with supply and/or transport of nutrients

complications with fetal metabolism

maternal malnutrition

• deficiencies in mom’s diet prior to and during pregnancy

“grandmother” effect

suggests that even if mother have adequate nutrition throughout their life and pregnancy, if their mother was undernourished during her pregnancy it increases the chances of giving birth to an offspring with congenital challenges

Rh Incompatibility

if mother is Rh- and fetus inherits Rh+ blood from father, the mother will develop antibodies against the foreign blood type; it won’t effect the current pregnancy but will inflict damage on subsequent pregnancies if not treated

• Erythroblastosis Fetalis

Erythroblastosis Fetalis

antibodies built up in mother can destroy RBC in future babies and cause anemia and jaundice

Treatment for Rh Incompatibility

Injection of rhogam

Mothers Emotional state

intense fear, prolonged anxiety or severe stress in mother during pregnancy can lead to complications and fetal abnormalities because sympathetic nervous system (SNS) restricts blood flow to uterine area

• children born from these conditions tend to be more prone to illness and physical problems throughout life

Genetic factors

• chromosome based disorders

• gene based disorder

chromosome-based disorders

meiotic-nondisjunction

• problems occur when chromosomes reproduce through meiosis if they don’t separate properly

Gene based disorders

ie: cystic fibrosis, club foot/talipes, spina bifida

Causes

• recessive disorders = receives defective gene from each parent (1/4 chance)

• Dominant disorders = defective gene overrides normal gene; ie: sickle cell anemia

• Sex-liked recessive disorders = defective gene is found on X chromosome, females are usually carriers but males display disorder

Klinefelter’s syndrome

XXY chromosome pattern

• those with the disorder lack sexual development and tend to be abnormally tall with relatively normal IQ

External/Environmental Factors

• maternal infections

• alchohol

• smoking

Maternal infections

diseases that mother acquires

• most dangerous for fetus are :

  • Cytomegalovirus (CMV) - results in blindness, deafness, and mental disabilities

  • Rubella (“3 day measles”) - results in growth retardation, boney legions, cataracts, and 80% display deafness

Alcohol

Completely avoidable, but the leading cause of birth defects in north america

• causes Fetal alchol spectrum disorder

Fetal Alcohol spectrum disorder (FADS)

marked facial defects, mental and behavioural disabilities, repetitive motions, can appear normal but can have motor developmental delays, attention deficits, memory difficulties

Smoking

• ↑ fetal death likelihood by 25-50%

• infants born to nicotine addicts are more fretful, less coordinated, less alert, less responsive to cuddling