Ch 17 Prematurity Flashcards
 Prematurity is defined as
Birth that occurs before 37 weeks
Immaturity of body systems
What is often used as a proxy for gestational age?
Birthweight
Birth weight classifications
Low birth weight 5lb 8oz
Very low birth weight 3lbs 5oz
Extremely low birth weight 2lbs 3oz
Micropremature 1lb 10oz
Gestational age classifications
Late preterm birth <37
Very preterm <33
Extremely preterm <29
Micropremature <26
Pre term infants are at risk for what kinds of neurological complications?
Periventricular hemorrhagic infarction (PVHI) Periventricular leukomalacia (PVL)
Describe sequence of PVHI
sequence of events begin with reductions in cerebral oxygen and blood flow (hypoxia ischemia)
result in intraventricular hemorrhage, and then PVHI
Other neurological complications in premature infants?
Post hemorrhagic hydrocephalus
Focalized neuronal injury
Cerebral ischemic lesions
Another kind of neurological complications in preterm infants?
Hypoxic ischemic encephalopathy with corresponding presentation such as:
poor Apgar scores
cord blood metabolic acidosis
need for resuscitation
How many grades of intraventricular hemorrhage are there
4
Grade I of IVH
Bleeding into germinal matrix
Grade II of IVH
Bleeding into ventricles, but no ventricular dilation
Grade III of IVH
Bleeding resulting in ventricular dilation
Grade IV of IVH
Large hemorrhage with PVHI in parenchyma
Risk factors for premature birth
Maternal hx of previous preterm birth
Short spacing between pregnancies multiple birth pregnancy
Maternal age younger than 16 older than 35
Maternal health problems (diabetes, obesity, HBP, kidney disease, heart disease, infections, stress)
Uterus or cervix abnormality
Alcohol, drugs, cigarette use
Low SES
Lack of prenatal care
Black
% of preterm births in US
10%
- 7% late preterm <37 weeks
- 3% <33 weeks
% of low birth weight in the US
8% low BW
1% very low BW
What factor accounts for the majority of preterm and low birth weight?
Multiple births
Infant mortality rate in the United States
6 per 1000 births
Second leading cause of death in infants under 12 months old
Premature birth
% of for infant deaths caused by premature birth
1/3
Preterm birth rate has been increasing or decreasing over recent years in the United States?
increasing
Which group has the highest rate of preterm birth, low birth weight and infant mortality?
Black
% of <25 weeks babies survive in high income countries
1/3
25-27 weeks baby survival rate in high income countries
80%
28-31 weeks baby survival rate in high income countries
96%
32-33 weeks baby survival rate in high income countries
98%
34-36 weeks baby survival rate in high income countries
> 99%, but 4x more likely to die than full term
biological viability for high income countries
23 weeks
biological viability for low/middle income countries
34 weeks
leading cause of death worldwide
premature birth
determinants of severity
birth weight use of prenatal and postnatal steroids gestational age in weeks neurological complications (grades III, IV IVH) access to NICU NICU stay familial/environmental factors (SES, education, maternal health) male vs female baby (male worse outcome) reduced gray and white matter volumes larger ventricular size
recovery course
first 8 hours are critical
50% of IVH occur in the first 6 to 8 hours of life
95% occur within first 4-5 days
assessment methods
ultrasound - GOOD detection of IVH, severe white matter injury (NOT sensitive to certain White matter injuries)
MRI - monitor brain dev, detect PVI and other injuries
CT, EEG
General Movement Assessment (GMA)
for kids younger than 5 months
combined with neonatal MRI to predict CP
assess spontaneous movements in children preterm
Hammersmith Infant Neurological Exam (HINE)
for kids > 5 months
combined with neonatal MRI to predict CP
Treatment
magnesium sulfate - assists with neurogeneration
synthetic surfactant - keep air sacs in lungs open during respiration
hypothermia and hyperbaric chambers - decrease incidence of HIE
inhaled nitric oxide - reduce incidence of bronchopulmonary dysplasia (BD)
postnatal steroid - prevent and treat respiratory complications CONTROVERSIAL!
complications in pre term
hypoxic ischemic neurological events chronic lung disease apnea of prematurity necrotizing enterocolitis (NEC) retinopathy of prematurity septicemia patentductus arteriosus respiratory distress syndrome pulmonary hypertension bronchopulmonary dysplasia
NP results for pre terms
IQ - variable but may be lower. increases with gestational age.
Academic functions - usually more challenges, special education, grade retention
attention - increased ADHD
processing speed - slow speed is common (white matter pathology in preterms)
language - semantic, crystallized language is ok; comprehension, fluency is worse; naming is hard; overall language progresses
visuospatial - usually bad because periventricular regions close to optic radiations and dorsal stream dysfunction
memory - slow acquisition, deficits recall; spatial memory deficits for micropremies; reduction in hippocampal volume
executive functions - working memory, planning, set shifting, vigilance, organization problems
sensorimotor - common deficits
emotions and personality - more problems than peers
SVT, PVT - not studied
germinal matrix
most common location of IVH in preterm
highly vascularized and highly cellular
below lining of lateral ventricle
cells migrate here during development, diminishes gradually and disappeared by 36 weeks
IUGR
poor fetus growth during pregnancy
fetus’ weight falls below 10th percentile
usually because fetus not getting enough O2 and nutrition from the placenta
abnormal development frontal brain region
lower IQ and NP impairment
Bronchopulmonary dysplasia (BPD)
chronic lung disease
tx by mechanical ventilator and supplemental O2
cog impairment in severe BPD
IVH
cog impairment and learning disability increases with severity of IVH (by grade)
can be detected by ultrasound
necrotizing enterocolitis
cell death of intestinal tissue when lining of intestinal wall dies and tissues fall off
offer most in preterm or sick infants
poor prognosis, 25% of cases die as a result
patent ductus arteriosus (PDA)
heart condition in which ductus arteriosus of the heart does not close
abnormal blood flow between aorta and pulmonary arteries
PVHI
venous infarction
complication of IVH
obstructs terminal veins, causes PVI and HVI
results in necrosis of periventricular white matter
PVL
ischemic injury to white matter surrounding lateral ventricles
lesions occur near MCA, PCA, ACA
abnormalities in the function of corticospinal tract
increases risk for CP
