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