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Pediatric Fundamentals
Prenatal Growth and Development
Drs. Greg and Joy Loy GordonJanuary 2005
Pediatric Fundamentals – Prenatal Growth and Development
Prenatal
Embryonic period first 8 weeks
Organogenesis 4th – 8th weeks
Ectoderm
Mesoderm
Endoderm
Pediatric Fundamentals – Prenatal Growth and Development
Organogenesis 4th – 8th weeks
Ectoderm
nervous system
skin
sweat and mammary glands
teeth
epithelial structures of eyes, ears, neck
Pediatric Fundamentals – Prenatal Growth and Development
Organogenesis 4th – 8th weeksMesoderm
somites
dermis and epidermis
cardiovascular system
urogenital system
spleen
adrenal cortex
Pediatric Fundamentals – Prenatal Growth and Development
Organogenesis 4th – 8th weeks
Mesoderm
somites
myotomes ->
segmental muscles of trunk
dermatomes ->
dermis of scalp, neck, trunk
sclerotomes ->
vertebral bodies, arches
abnormal induction -> spinal bifida
Pediatric Fundamentals – Prenatal Growth and Development
Organogenesis 4th – 8th weeks
Endoderm
epithelia
digestive
respiratory
bladder
parenchyma
liver
pancreas
thyroid gland
parathyroid glands
thymus
salivary glands
Pediatric Fundamentals – Prenatal Growth and Development
Developmental Abnormalities
congenital diaphragmatic hernia (CDH)
esophageal atresia
spina bifida
Hirschsprung’s disease
omphalocele
gastroschisis
Pediatric Fundamentals – Prenatal Developmental Abnormalities
Congenital diaphragmatic hernia (CDH)
1 in 2,500 live births
85% left side of diaphragm
defect in closure of pleuroperitoneal canal
impaired lung growth
prenatal (intrauterine) repair possible
Pediatric Fundamentals – Prenatal Developmental Abnormalities
Esophageal atresia
failure of proliferation of esophageal endoderm in 5th week
5 types – some with associated tracheoesophageal fistula
+ E = H-type(7%)
80%10%1% 2%
Pediatric Fundamentals – Prenatal Developmental Abnormalities
Spina bifida
failure of closure of posterior neural tube during 3rd embryonic week
mild: spina bifida occulta
severe: meningomyelocele
80% lumbosacral
in utero repair described
Pediatric Fundamentals – Prenatal Developmental Abnormalities
Hirschsprung’s disease
defect in neural crest migration
leads to paralysis of that segment of colonwith subsequent proximal dilation
Pediatric Fundamentals – Prenatal Developmental Abnormalities
1 in 2,500 live births
failure of return of midgut
from yolk sac to abdomen
by 10 weeks
often associated with other abnormalities
Omphalocele
Pediatric Fundamentals – Prenatal Developmental Abnormalities
1 in 10,000 live births
abdominal wall defect
between developing rectus muscles
just lateral to umbilicus
right side
may be due to abnormal involution of right umbilical vein
during 5th and 6th weeks
usually not associated with other defects
Gastroschisis
Pediatric Fundamentals – Prenatal Growth and Development
Consequences of maternal disorders on intrauterine developmentepilepsyhistory of previous child with neural tube defectdiabetes mellitussubstance abuse
alcoholtobacco cocainebenzodiazepines
infectious diseasesrubellatoxoplasmosishuman immunodeficiency virus (HIV)herpes simplex
Pediatric Fundamentals –Consequences of Maternal Disorders
Epilepsy
Congenital anomalies 2 to 3 times more frequent
Appear to associated with increase risk of malformation:
phenytoin
valproic acid
multidrug therapy
Neural tube defects (e.g. spina bifida)
valproic acid
carbamazepine
low dose folate may decrease risk
Pediatric Fundamentals – Consequences of Maternal Disorders
History of previous neural tube defect:
Risk of subsequent neural tube defect
increased 10 times
Pediatric Fundamentals – Consequences of Maternal Disorders
Diabetes mellitus
Increased incidence of
stillbirth
congenital malformations
risk of major malformation
(8 times greater)
increased rate of high birth weight
hypertophic cardiomyopathy in IDM
Pediatric Fundamentals – Consequences of Maternal Disorders
Substance abuse
alcoholFetal alcohol syndrome
intrauterine growth retardation (IUGR)
microcephaly
characteristic facies
CNS abnormalities
with intellectual deficiency
Increased incidence of other major malformations
Pediatric Fundamentals – Consequences of Maternal Disorders
Tobacco Low birth weight
Cocaineprematurity
clinical seizures
EEG abnormalities
neurobehavioral abnormalities
cerebral hermorrhagic infarction
Benzodiazepines: no clear teratogenic link sedation and/or withdrawal symptoms reported
Pediatric Fundamentals – Consequences of Maternal Disorders
Infectious disease
Rubella
Chromosomal abnormalities
IUGR
Ocular lesions
Deafness
Congenital cardiomyopathy
Especially with infections before week 11
Pediatric Fundamentals – Consequences of Maternal Disorders
Infectious disease
Toxoplasmosis
IUGR
Nonimmune hydrops
Hydrocephalus
Microcephally
Later neurologic damage
Prompt spiramycin Rx until after delivery decreases risk 50%
Pediatric Fundamentals – Consequences of Maternal Disorders
Infectious disease
Human immunodeficiency virus (HIV)
Transmission to fetus: 12 – 30%
less if mother taking Zidovudine
(no teratogenesis reported)
First signs appear at 6 months of age
Median survival 38 months
Pediatric Fundamentals – Consequences of Maternal Disorders
Infectious disease
Herpes simplex
Neonatal infectionsTwo-thirds caused by asymptomatic genital infectionHigh morbidity and mortality
Seizures Psychomotor retardation Spasticity Blindness Learning disabilities Death
Maternal active infection: C-section indicated to decrease risk
Pediatric Fundamentals – Consequences of Maternal Disorders
IUGR
3-7% of all pregnancies
Major cause of perinatal morbidity and mortallity
Prognosis depends on specific cause
Up to 8% have major malformations
Head growth important determinant of neurodevelopmental outcome
(IUGR + HC < 3rd%ile -> abnormal neurodevelopment likely)
Hemodynamic changes and/or infectious disease often involved
Pediatric Fundamentals – Prenatal Growth and Development
Knowledge of normal and abnormal development needed for best intraop care of
neonate with congenital malformation or complication of premaurity
Diagnosis and prenatal transfer of fetus with major malformation now possible
Improvements in neonatal care →
lowering of gestational age compatible with long-term survival
more premature infants presenting for anesthesia for surgery